CU Biochem Course and NAMA Flashcards
What is the difference between classic PKU, mild PKU< and hyperpheylalaninemia?
Untreated Phe levels:
>1200umol/L - classic PKU
600-1200umol/L - mild PKU
<600umol/L - hyperphe
Mousy odored urine, light hair, eczema, developmental delay, white matter hyperintensities
Untreated PKU
- treatment needs to start within 1 month of life
- “pseudoleukodystrophy”
What is pegvaliase
Enzyme substitution for PAH deficiency (PKU)
- plant enzyme (phe ammonia lyase)
- Goal to enhance Phe tolerance and normalize diet
- still need tyrosine
- Approved for 16+
Elements of PKU diet
Low Phe
Supplement tyrosine and tryptophan (share same large neural AA transporter as Phe)
What is a goal of sapropterin trial in PKU?
20mg/kg/day
Infant: 24 hour trial -> >30% reduction in Phe = positive (no dietary changes)
Adult: 48hr to 30 day trial
Mutatons in which subunit of BCKDH can be thiamine (B1) responsive?
E2 subunit
What is the role of IV destroxe (glucose) in metabolic decompensation?
- Prevent gluconeogenesis that drives protein breakdown
- Provide calories
- Drives insulin production (anabolic)
Tyrosine aminotransferase deficiency
Tyrosinemia type 2
PAA: high Tyr, Phe
UOA: 4-OH phenylpyruvate/lactate/acetate
- corneal lesions, hyperkeratosis
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UOA: 4-OH phenylpyruvate, 4OH phentyllactate, 4OHphentylacetate
Tyrosinemia type II
Tyrosine aminotransfearse deficiency
TAT gene
PAA: high Tyr, Phe
4-hydroxyphentylpyruvic dioxygenase deficiency
Tyrosinemia type III
HPD gene
- PAA: high Tyr, Phe
- Uncertain clinical significance, may have keratitis
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Renal fanconi, liver/renal disease, porphyric crisis, hepatocellular carcinoma
Tyrosinemia type I
Fumarylacetoacetate hydrolase deficiency
FAH
- High AFP, SUAC, Met (liver disease)
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high AFP, methionine, aaminolaevulinic acid (ALA)
Tyrosinemia type I
FAH
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What are the 3 presentations for tyrosinemia type I?
- Hepato: early severe liver disease
- Renal: rickets (renal fanconi)
- Acute intermittent: porphyria like attacks
What are the toxic compounds in tyrosinemia type I?
FAH deficiency
- Fumarylacetoacetate, Maleylacetoacetate, Succinylacetone
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Which steps in porphyrin synthesis does SUAC inhibit?
ALAD and HMBS
What is 2-nitro-4-trifluoromethylbenzoyl - 1,3- cyclohexane-dione used to treat?
Tyrosinemia type I
2-nitro-4-trifluoromethylbenzoyl - 1,3- cyclohexane-dione
NTBC = nitsinone
- inhibits 4-OHphentylpyrvic acid dioxygenase
- Goal: blood level >40 (enzyme inhibition 99%); SUAC suppression
- restrict Phe/Tyr to goal <600 umol/L in blood
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corneal crystals, plantarpalmar hyperkeratosis with pits
Type II or III tyrosinemia
TAT (tyrosine aminotransferase), HPD (hydroxyphenylpyruvate dioxygenase)
- May also have ID/seizures if untreated
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If NBS shows high Tyr and normal SUAC, what should you do next?
Repeat at 6 weeks -> if normal this is transient tyrosinemia of newborn
-> if abnormal work up tyrosinemia type II and III
What vitamin will 50% of Cystathione beta syntase deficiency respond to?
B6 - pyridoxine
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What is treatment of homocystinuria is B6 unreponsive?
Folate (B9)
B12 if deficient
Low protein (met)
Betaine (alternate remethylation pathway)
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Which UCD has fair fragility (Trichorrhexis nodosa) + rash?
ASL deficiency
- also increased liver disease
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Which UCD enzymes are in the mitochondria?
N-acetylglutamate synthetase
Carbamoyl phsophate synthetase
Carbonic anhydrase 5A (CAVA) - Makes bicarb necessary for carboxylases (including CPS)
Ornithine transcarbamylase
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Why does citrulline bruild up in citrin deficiency?
Aspartate is stuck and mitochondria and unable to conjugate with citrulline in cytoplasm (ASS) to form arginosuccinate.
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Why is Lys high in OTC deficiency?
Shortage of 2-oxoglutarate
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Gold standard testing for OTC in females
Liver enzyme funciton testing
- Molecular testing cannot find mutation in 10%
- Orotic acid/glutamine may be normal
Why does Carbonic anhydrase 5-A deficiency cause hyperammonemia?
CAVA synthesizes bicarb in mitochondria used by CPSI -> Proximal UCD
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What is phenylbutyrate?
Prodrug to phentylacetate -> conjugates to glutamine
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Which UCD presents with spastic diplegia and intellectual disability?
Arginase deficiency
+ growth arrest
- check PAA when working up DD!
What are the cofactors for glycine cleavage system?
Lipoate and pyridoxal-Phosphate
- Deficiency can cause variant NKH
high CSF/serum glycine, high homocysteine, high MMA
HCFC1 - Cobalamin X
- XL
- Transcription factor for glycine cleavage system and Cbl pathway
What drugs should be avoided in NKH?
Valproic acid and vigabatrin -> inhibit residual enzyme activity
(both can cause iatrogenic glycine elevation)
98% of NKH are caused by variants in what 2 genes?
GLDC and AMT
P and T protein
What is treatment for NKH?
Benzoate (conjugates with glycine to form hippurate) -> goal plasma glycine 120-300uM
Glycine restriction
Ketogenic diet (glycine is gluconeogenic substrate)
NMDA blockade: Dextromethorphan, ketamine
What is serine synthesized from?
3-phosphoglycerate (glycolysis intermediate)
3PG Dehydrogenase -> Phosphserine aminotransferase -> phosphosering phosphatase
CSF: low glycine, low serine
Serine synthesis defect
PGDH, PSAT, PSPH
- Severe hypomyelination and epilepsy
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What is the treatment for neu laxova syndrome?
Serine supplementation + glycine supplementation
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What is the vulnerable window in GA1
3 months - 2 years
- Up to 6yo can be affected
High Glutaric acid, 3-OH glutaric acid
GA1
GCDH deficiency
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What is C5DC?
Glutaryl carnitine
- look for GA1
What is treatment for GA1?
1) avoid catabolism
2) low lysine/trytophan
3) Carnitine
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What does 2-aminoadipic semialdehyde dehydrogenase deficiency cause?
Pyridoxine dependent epilepsy
ALD7A1 - antiquitin
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High aminoadipid acid semialdehyde, pipecolic acid, 6-oxo-pipecolate
pyridoxine dependent epilepsy
ALD7A1
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What is the second most common B6 responsive epilepsy? (after ALDH7A1)
Pyridoxine 5 phosphate oxidase deficiency
PNPO
- Converts pyridoxine to active form
- Normal cognitive development (not true in ALDH7A1)
What is the treatment for alpha-aminoadipic semialdehyde DH deficiency or pyridoxamine-5-phosphate oxidase deficiency?
Pyrixodine depedent epilepies (ALDH7A1 and PNPO)
- Will always respond to pyridoxal phosphate (active form)
- might repsond to pyridoxine
Which pathways are mostly affected in riboflavin deficiency?
ETFDH (GA2)
FAOD
BCAA metabolism
Complex I
Axonal neuropathy, hearing loss, bulbar weakness, myopathy
Riboflavin transporter defects
RFVT2 and RFVT3
Brown-Vialetto- Van Laere
- Tx: Riboflavin
Low 5-methyltetrahydrofolate in CSF
Folate transporter deficiency (FOLR1) or Kearns-Sayre
- Ataxia, epilepsy, demyelination
megaloblastic anemia, diabetes, SNHL in infancy
Thiamin-responsive megaloblastic anemia
SLC19A2
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3 thiamine reponsive encephalopathies
TPK1
SLC19A3
SLC25A19 (also severe congenital microcephaly)
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What does G6Pase translocase deficiency cause?
GSD1b
- GSD1 + neurtropenia
GSD1a is caused by G6Pase (most common GSD)
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Are glucagon levels low or high in GSD1?
Elevated
Glucagon drives gluconeogenesis and glycogenolysis, both are defective in G6Pase deficiency
- Insulin is low until fed
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Doll like face, buttock fat pad accumulation, hepatomegaly, nephromegaly, hypotonia, bleeding tendency
GSD1
- No nephro/hepatomegaly in CDG-PMM2
Compare Von Gierke and Cori disease
GSD1 (G6Pase) vs GSD3 (amylo-1,6-glucosidase)
- GSD3 has milder hypoglycemia (gluconeogenesis intact), but more early liver dysfunction
- Give high protein diet for GSD3 (glucogeogenesis)
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What is the mechanism of injury in Anderson disease?
GSD4 - a-1,4-glucan-6-glucosyltransferase deficiency (branching)
- Unbanched glycogen (polyglucosan) build -> toxic -> hepatosplenomegaly
- other GSDs have branched glycogen buildly
Liver pathology findings for Andersen’s disease
GSD4 - branching enzyme
- Unbranched glycogen (polyglusocan) accumulation
- path: PAS stain positive, diastase-resistant with amylopectin-like inclusions
Which GSDs have postprandial hyperglycemia?
GSD0 - unable to store BG as glycogen
What can patients with fanconi Bickel syndrome get that GSD1 patients canno?
Fructose
- Fanconi bickel = glucose/galactose transporter defect
- in GSD1 fructose cannot be used because it is convered into G6P
Treatment for tauri disease?
Avoid sugars/glucose - no NOT give D10 when sick
- Glucose is high but not sensed by mitochondrial/cannot be used for glycolysis.
- FAO inhibited by high glucose levels
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In which GSDs should you avoid giving excess glucose?
GSD4 (Andersen) and GSD9 (Tauri)
- Andersen -> more glucose -> more polyglucosan; give proteins to promote gluconeogensis instead
- Tauri -> Glycolysis is blocks, reduce glucose to release inhibition on FAO
microcephaly, thin upper lip, long philtrum, wide nasal bridge, DD, leigh syndrome
Pyruvate dehydrogenase deficiency
Most common X linked
- Fetal alcohol syndrome-like face + leigh syndrome
- high pyruvate -> high lactate + alanine
- Lacate/pyruvate ratio low
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Treatment for PDH deficiency
Ketogenic diet, thiamine, carnitine, lipoic acid
Name the 3 glyconeogenic enzymes
Pyruvate Carboxylase, Fructose 1,6 bis phosphatase, Glucose-6-phosphatase
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Cystic brain lesions, FTT, metabolic acidosis
PAA: High Cit, Ala, Lys, Pro
UOA: 2-oxoglutaric acid (aKG)
High lacate/pyruvate with increased ratio >20
high acetoacetate/betahydroxy-butyrate ratio
High ammonia
Pyruvate Carboxylase deficiency
- Biotin Dependent
- TCA cycle and gluconeogenesis affected
High lacate -> high ala, proline (proline oxidase suppressed)
Low OAA (precursor) -> low aspartate and glutamate
Low aspartate -> high citrulline and ammonia
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Compare F1,6BP deficiency with HFI
- F1,6BP can tolerate more fructose
- F1,6BP presents more like GSD1 - F1,6BP buildup inhibits G6Pase
- FBP: Pseudohypertriglyceridemia, high glycerol, glycerol 3 phosphate
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What is the pathophys of HFI?
Aldolase B deficiency
Toxic accumulation of F1P -> impaired gluconeogensis and glycogenolysis -> lactic acidosis, hypolgycemia, liver failure
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Promoter deletion + N314D/Q188R
Biochemical (Duarte) Galactosemia
GALT (~25% activity)
UOA: high glycerol-3-phosphate, glycerol
high TG
high alanine, ketones
Fructose 1,6 BP
Glycerol-3-phosphate is not seen in glycerolkinase
Contrast HFI and FBPase deficiency
HFI: childrne have no cavities (Aversion to sweets), FTT with fructose ingestion, RTA
FBPase: can tolerate fructose, no renal involvement, UOA with glycerol/glycerol-3-phosphate
Q188R
K285N
L195P
classic galactosemia
GALT (<1% activity)
- early e.coli sepsis, FTT, liver disease
+ Premature ovarian insufficiency and DD
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S125L
Variant galactosemia
GALT (1-10% activity)
Same early presentation (e-coli sepsis, FTT, liver disease etc)
- Normal development/reproduction
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Urine polyol analysis: high ribitol, D-arabitol, erythritol, sedoheptulose
Transaldolase
TALDO
Liver, HSM, anemia, thrombocytopenia, congenial anomalies
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Urine polyol: high ribitol, D-arabitol
Ribose-5-P Isomerase
RPIA
- Leuckoencephalopathy, ataxia, neuropathy
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What are the steps of ß-Oxidation?
1) Dehydrogenase (create 2,3 double bond)
2) hydratase (add 3-OH)
3) dehydroganse (create 3 double bonded O)
4) thiolase (remove ketone)
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Treatment for FAODs
- low fat diet
- avoid catabolism
- triheptanoin (Long chain and above) - can freely diffuse into mitochondrial and bypass carnitine shuttle/long chain breakdown
- Carnitine (allows urine clearance of FA)
What is OCTN2 deficiency?
Primary carnitine deficiency (Carnitine transporter)
(SLC22A5)
- carnitine cannot be reabsorbed in kidney -> unavailable in liver/muscle/heart
- Presents with hepatic encephalopathy, cardiac, hypoglycemia, rhabdo
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What should be done if a baby is NBS positiove for low carnitine but has normal plasma F/T carnitine testing?
Screen for mother with primary carnitine deficiency
- Carnitine comes from breastmilk for young infants
- Mothers w/ carnitine deficiency will have NBS positive child and are at risk for sudden death
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UOA: Hexanoylglycine
MCAD
ACADM
ACP: high C6, C8, C10:1
Why are dicarboxylic acids elevated in urine in FAOD?
Long chain FAs build up in cytoplasm go into microsomes -> gets converted into dicarboxylic acids
What is the next step if NBS is positive with elevated C14:1 but plasc ACP is normal?
VLCAD gene sequencing (ACP may be normal between episodes)
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FAOD + neuropathy, RP, and maternal preeclampia/HELLP/fatty liver
LCHAD/TFP
- hydroxylated FAs can flow into mom and accumulate
- TFP also modified cardiolipin (may explain extra symptoms)
if NBS is high for C16OH and ACP/UOA are normal, what is the next step?
Sequencing for LCHAD/TFP - cannot rule out wth ACP alone
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UOA: High ethylmalonic acid, n-butrylglycine, and methylsuccinic acid
- SCAD
- Isobutyryl glycinuria (+ high isobutyrylgylcine)
- Ethylmaloni encephalopathy (+ persistent lactic acidosis) - ETHE
What is the final electron acceptor of dehydrogenases?
ETFDH
- Causes GA2 -> mulitiple DH issues -> multiple chain length elevations of ACP
- Riboflavin is cofactor
What are the main ketogenic AAs?
Leucine, isoleucine, lysine
Hypoketotic hypoglycemia, dicarboxylic aciduria, 4-hydroxy-6-methyl-2-pyrone
- normal ACP
3-Hydroxy-3-emethly-glutaryl-CoA synthase deficiency (HMG-coa Synthase)
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UOA: 3-hydroxy-3-methylglutaric acid, 3-methylglutaric acid
- hyperammonia, hypoketotic hypoglycemia
2-Hydroxy-3-methlyglutayl-CoA Lyase deficiency (HMG-coa Lyase)
- high HMG and MG (3-hydroxy-3-methylglutaric acid, 3-methylglutaric acid)
- C6DC (3 methylglutaryl-carnitine), C5OH (3-OH-isovaleryl carnitine)
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high D-3-hyroxybutyrate, tiglylglycine, 2-methyl-3-hydroxybutryrate, 2-methylacetoacetate
beta-ketothiolase (T2)
- ACAT1
- High ketones during illness + isoleucine intermediates
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High ketones with normal dicarboxylic acids
Disorders of ketolysis
- physiological ketosis comes from FAO -> thus dicarboxylic acids (adipid, suberic, and sebacic) also build up
- HIgh ketones with normal dicarboxylic acids -> usually SCOT deficiency
High ketones during fed and fasting state
Succinyl-Coa - oxoacid-Coa transferase (SCOT)
SCOT/OXCT1 gene
- Do not see elevated dicarboxylic acids (adipic, suberic, sebacic) which are seen in physiological ketosis
DDx: Monocaroboxylic transporter 1 (MCT1) deficinecy -> ketone transporter
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What is Monocarboxylic Transporter 1 (MCT1) deficiency?
Ketone transporder defect
SLC16A1
- looks similar to SCOT -> episodic ketoacidosis
- Increased acetoacetate + 3 OH butyric acid, normal dicarboxylic acids
Renal fanconi, renal failure, cornea crystals, hypothyroidism, hypogonadism, myopathy
Cystinosis
Lysosomal Cystine transporter
- Tx Cysteamine eyedrops + Tablets
- Cysteine (Cystine + Cysteamine) has own transporter; another cysteine can be added and use Lysine transporder
GLA N215S
Cardiac Variant Fabry
GLA A143T
VUS Fabry
- Most common on NBS
Alkylglycerone 3-phosphate acyltransfearse deficiency
GNPAT - RCDP
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Alkylglycerone 3-phosphate synthase deficiency
AGPS
- RCDP
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Most common cause of RCDP
PEX7
- Low plasmalogen, also high phytanic acid
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Fatty Alcholol Reductase deficiency
RCDP without RCDP
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PEX5L deficiency
RCDP
- mutation in specific long isoform of PEX5 - mutations in exon 9
- Results in abnormal PEX7 activity
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Metaphyseal flaring, epiphyseal stippling, coronal vertebral clefts, mineralization of intervertebral disks
RCDP
- ARSE - XL -Male
- Sterol-8-isomerase - XL - Females (male lethal)
- Wafarin/VitK, EtOH, Phenytoin
high oxalate, glyoxalate
Primary hyperoxaluria type I
AGT
Alanine-glyoxylate aminotransferase - peroxisomal enzymes
- Renal stones + nephrocalcinosis
- Tx: Pyrixosone, Hydration, Liver/Kidney transplant
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Neuropathy, loss of night vision, deafness, conduction defects, short metacarpals/metatarsals
Adult refsum disease
- Phytanol-CoA hydroxylase deficiency
- High phytanic (found in animal fats and plants), low pristanic acid
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Which amino acides do glycosylation occur on?
N-linked - Asparagine
O-linked - Serine or threonine
Which organelles does glycosylation occur in?
Early - cytosol and ER (Type I isoelectric focusing pattern)
Late - Golgi (Type II pattern)
What methods to defect CDG is more sensitive and specific than isoelectric focusing?
Mass Spec
- Can see both N and O linked CDGs
- Can use flow-intection electrospray ionization to digest N-glycan off protein and get more specific results
What does phosphomannomutase do?
PMM2 -> converst mannose 6P to mannose 1P
Causes CDG
Which CDG causes protein losing enteropathy and hyperinsulinism with no neurological diasease
MPI - CDG1b
- treat w/ mannose
Which CDG is associated with elevated alk phos?
GPI anchor disorders
PIGA, PIGN, PIGO
- Seizures and DD
m.8993 T>G
Leigh syndrome - ATP6
m.3243 A>G
MELAS
rRNA leu
- Diabetes + hearing loss most common
- Complex I, III, IV deficiency
- Treat w/ Arg/Cit/Tauring
m.8344A>G
MERRF
tRNA Lys
+ lipomas
m.1555G>A
Hearing loss when exposed to aminoglycosides
(Mitocondria are derived from bacteria symbiotes!)
Homoplasmic m.11778 G>A (MT-ND4)
LHON
- Males > females
- incomplete penetrance
names 2 mtDNA deletion syndromes
Kearns-Sayre = CPEO + conduction block, RP, diabetes, renal, ID, hearing loss
Pearson Syndrome = KSS + sideroblastic anemia and exocrine pancreas dysfunction
SDH deficiency
AD paraganglioma + pheo
AR Leigh syndrome
Leigh syndrome + hypertrichosis/hirsutism
SURF1
- nuclear gene involved in complex IV assembly
- most common leigh gene
X-linked leigh syndrome
Pyruvate dehydrogenase deficiency
Tx - thiamine and ketogenic diet
- Males = mild mutations (severe mutations lethal)-> leigh syndrome, normal brain structure
- Females = het for severe mutations -> structural abnormalities, normal lactate (X inactivation)
POLG related disease
Alpers syndrome
- Multisystemic with many neurologicalm manifestations
- Polymerase Gamma
- VPA use can precipitate liver failure
- mtDNA depletion + Complesed I/III/IV deficiency
Steroid resistant nephrotic syndrome
CoQ10 synthesis defect
- ADCK4, PDSS2, COQ2, COQ6
Non-compaction cardiomyopathy, neutropenia, myopathy + high 3-methylglutaconic acid
Barth syndrome
TAZ (X Linked)
What does CblJ and CblF deficiency cause?
Combined HCy and MMA
- Cbl transport out of lysosome into cytosol where CblC is
- Serum B12 levels low - but NOT B12 deficiency
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What does Methylmalonyl CoA Epimerase deficiency cause?
MMA and PA
- Slight elevation in MMA (only D-Methylmalonyl=CoA high) and proximal buildup of PA + 2-methylcitrate (secondary PA metabolite)
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What should be ruled out if baby presents with NBS high MMA but no mutation is found?
Maternal B12 deficiency
What are the first steps after diagnosing sick child w/ MMA/PA?
- Determine B12 resonsiveness with hydroxocolbalamin
- Can try biotin if PA suspected (PA Carboxylase)
Bulls eye maculopathy
CblC (rarely CblD)
Bulls eye maculopathy can progress to RP and optic nerve atrophy despite treatment
Macocytic anemia, pancytopenia, high MMA, high HCy
Transcobalamin 2 deficiency
TCN2
- Treat with OH-Colbalamin injections
- Looks like neonatal leukemia/SCID
- TC2 colbalmin receptor deficiency tends to be milder/transient
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What Cbl defects can have low B12 levels?
Cbl J and Cbl F
- abnormal lysosomal efflux
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What is CblX?
HCFC1 and epi-cblC mutations
HCFC1 is X-linked
- Promoters/regulators of CblC expression
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What is the first clinical sign of MSUD?
Maple syrup odor in ceruloplasmin
most common creatine disorder
Creatine transporder deficiency
XL - transports GAA (produced in liver) into brain/muscle
- autisim
- 1-2% of ID in males
- variable sieizures
- usually achieve motor sckills, may have decreased muscle bulk
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Arginine Glycine Amidinotransferase Deficiency
Rarest Creatine synthesis disorder
- Arginine + glycine -> Ornithine (negative feedback) + GAA
- Static encephalopathy
- Seizures rare, no regression
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AGAT vs GAMT vs CT
AGAT tends to be static with no regression, also less seizures; may have FTT
GAMT tends to have progression, intractable epilepsy, and movement d/o, no FTT
Creatine transporter (XL) usually delay + autism (may have FTT)
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Low GAA, Low/nl Creatine
Arginine Glycine Amidinotransferase deficiency
- static encephalopathy, no regression, rare seizures
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high GAA, low/nl creatine
Guanidinoacetate methyltransferase deficiency
- Epilepsy, regression, movement disorder
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Normal GAA and Creatine.
Urine Creatine/Creatinine ratio > 1600
XL Creatine Transporder Deficiency
ID/Autism
- Creatine cannot get into musclae cells were it gets converted into createnine
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Treatment for creatine synthesis defects
AGAT/GAMT -> Creatine monophosphate supplement
GAMT -> Arginine restriction, ornithine supplement to decrease production of GAA (Ornithine is inhibitor of AGAT)
Creatine Transport - no therapy
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High Hypoxanthine, Xanthine, and Uric Acid
Lesch Nyhan (HGPRT)
Hypoxanthine Guanine Phosphoribosyltransferase deficiency
- Hypoxanthine and Guanine recycline defect
- Neuro + Gout + nephrolithiasis
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High succinyladenosine (S-Adenosine) and SAICA Riboside
Adenylosuccinase/Adenylosuccinate lyase deficiency
ADSL
Seizure/ID
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What are the main phenotypes of purine metabolism disorders?
Neurological
Immunological
Gout/Renal Failure
High inosine and guanosine, low uric acid
Purine Nucleoside Phosphorylase Deficiency
PNP
Neuro + immunodeficiency
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High adenosine + adenine
Immunodeficiency
Adenosine Deaminase Deficiency
ADA
- NBS TRECs
- SCID
- Enzyme replacment (PEG-ADA)
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Name 3 purine disorders that cause primarily nephrolithiasis
PRPPS - Phosphoribosyl-pyrophosphate synthetase superactivity (high urine acid)
XO - Xanthine Oxidase (high xanthing, hypoxanthine, low uric acid (high in HGPRT))
APRT - Adenine phosphoribosyltransferase deficiency (high adenine)
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What is cyclic pyranopterin monophosphate used to treat?
Molybdenum cofactor deficiency (cPMP)
Which purine disorders present with SCID?
ADA - high adenosine, adenine
PNP (PNP = neuro + scid) - high inosine, guanosine
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High xanthine, hypoxanthine
Low uric acid
- Xanthine Oxidase deficiency - renal stones
- Molybdenum Cofactor deficiency - neuro, lens dyslocation
(Xanthine/Hypoxanthine high in HGPRT, but urine acid also high)
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High succinyladenosine
ADSL deficiency
- neuro
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High adenine, normal adenosine
APRT deficiency
- nephrolithiasis
(if adenosine also high then ADA)
High uric acid and hypoxanthine
PRP Superactivity
- gout + stones
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Main neurological Purine disorders?
Molybdenum cofactor (High xanthine, hypoxanthine, low uric acid)
ADSL (Succinyladenosine)
HGPRT (high xanthine, hypoxanthine, uric acid)
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anemia + orotic aciduria
Hereditary orotic aciduria
UMPS
Uridine monophosphate synthease deficiency
- Anemia unresponsive to B12, folate, iron
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High uracil and thymine
Dihydropyrimidine Dehydrogenase Deficiency
Neuro, FTT, epilepsy
- may be asymptomatic, 5FU toxicity
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high dihydrouricil, dihydrothymine, uracil, thymine
Dihydrophrimidinase deficiency
Asymptomatic, may be neuro, epilepsy
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mitochondrial disease with high thymidine levels
MNGIE
Thymidine phosphorylase deficiency
High dihydrouracil, dihydrothymine, urediopropionic and urediosiobutyric acid
Ureidopropionase Deficiency
UPB1
- asympatomatic vs neuro + seizure + dystonia
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Low dopamine and VMA, high 3-o-methyldopa
AADC deficiency
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Low Homovanillic acid/5-HIAA ratio
Tyrosine hydroxylase deficiency
(Tryptophan hydroxylase is normal)
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X Linked monoaminemetabolism defect
MAOD
- usually mild ID with aggressive behavior
high CSF and plasma GABA
hypomyelination, movement disorder, EIEE
GABA transaminase deficiency
ABAT gene
- 2-pyrrolidinone biomarker
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High 4-hydroxyisobutyric acid, high GABA
Succinic Semialdehyde Dehydrogenase Deficiency
Neurodevelopmental, EIEE
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Why do SLOS patients have dysmorphology?
Cholestrol and 7DHC are activators of SHH
SLOS -> low cholesterol, high 7DHC
RCDP + ichthyosis, coarse hair
XL CDP -> male lethal
Sterol 7.8 isomerase
High Lathosterol
Lathosterolosis
SLOS like
Sterol 5 desaturase
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high desmosterol
Desmosterolosis
SLOS like
DHCR24
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SLOS like cholesterol disorders
SLOS - DHCR7
Lathosterolosis - SC5DL (5 desaturase)
Desmosterolosis - DHCR 24
- squaline synthase deficiency also looks similar (rare) - FDFT1
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High mevalonic acid
Mevalonic Kinase (MVK) deficiency
- High IgD w/ recurrent fevers
- Dysmorphic, RP, Ataxia + immune
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High lanosterol and dihydrolanosterol
Antley Bixler
POR/CYP450
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high sitosterol, campesterol
Sitosterolemia- Sterol transporter defect
ACBG5, ACBG8 (AR)
Increased plant sterol absorption
- Xanthomas (including buttock), artherosclerosis, splenomegaly, arthralgies
Cholesterol disorders with primary severe skin manifestations
SC4MOL - sterol C4 methyoxidase (MSMO1)
CHILD syndrome - 4-demethylase (NSDHL)
- high 4 methylsterols
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Where are NPC1 and NPC2 located?
NPC is disorder of cellular cholestrol trafficking -> accumulation of cholesterol esters in lysosomes
NPC1 - late endosomal membrane protein
NPC2 - lysosomal cholesterol binding protein
3 presentations of NPC
1) Hydrops
2) neonatal liver disease
3) late onset neurological + hepatomegaly
“sea blue histiocytes”
Positive Filipin Stain
NPC
diarrhea, cataracts, DD, hepatitis, xanthomas, neurodegeneration
High Cholestanol
CTX
Sterol-27 hydroxylase (CYP27A1)
- Bile acid metabolism block -> buildup of cholestanol in CNS
- Treat with chenodeoxycholenic acid
Low LDL cholesterol and neurological deterioation
Abetalipoproteinemia
MTTP (microsomal triglyceride transfer protein)
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Sebelipase Alfa
ERT for Lysosomal Acid Lipase Deficiency
Wollman or Cholesterol Ester Storage disease
- LSD with adrenal calcifications, microvesicular steatosis
Orange Tonsils
Tangier Disease
ABCA1
low HDL
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acrodermatitis, diarrhea, alopecia, FTT
Acrodermatitis enteropathica
Zinc deficiency, Transporter defect (ZIP4 or ZnT2)
ZIP4- Symptom onset when weened from breastmilk
ZnT2 - Symptom onset when baby is on breastmilk
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ATP7A deficiency
Menkes
X-linked
Enterocyte Cu transporter -> deficiency
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ATP7B deficiency
Wilson’s
Liver/CNS Cu secretory protein
- Liver overloaded with Cu, serum Cu low, urine Cu high
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Polycythemia, Parkinsonsim, Dystonia
Manganese toxity (and transporter defects)
SLC30A10 - + liver disease (cannot leave liver)
SLC39A14 - no liver disease (not absorped by liver)
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What metabolites tell you about cytoplasmic NADH/NAD ratio?
Lactate/pyruvate
What does 3-hydroxybutyrate/acetoacetate ratio tell you?
Intramitochondrial NADH/NAD+ ratio
high deoxyuridine, deoxythymidine levels
MNGIE
Thymidine Phosphorylase deficiency
high thiosulfate, hydrogen sulfide, ethylmalonic acid, C4/C5 acyl-carnitines
Ethylmalonic encephalopathy
ETHE1 persulfide dioxygenase
Normal complex 1-4 activity, low combined complex 2-3 and 1-3 activity
CoQ10 deficiency
What are FGF21 and GDF15 used for?
Markers of mitochondrial dysfunction
- useful for mtDNA maintenance/depletion/translation disorders
- Not useful for complex subunit disorders
SURF1 mutation cause what disease? What mito complex finding?
Leigh syndrome
isolated complex IV decrease (Complex IV assembly factor)
What mito complex pattern do you see in POLG?
Decreased 1, 3, and 4
(complex 2 is nuclear encoded)
Treatment for MELAS
Arginine, Citrulline, Taurine (Natural Taurio-methyl uridine modification is impaired by 3243 mutation)
How do you treat NKH?
Sodium Benzoate (conjugates with glycine to form hippurate)
NMDA blockade
What is the end product of AA transamination?
Ammonia (NH3) and a-ketoacid (R-CO-COOH)
Why is lysine high when ammonia is high?
2KG used to synthesize glutamate instead of saccharopine
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What is rate limiting step of urea cycle?
NAGS -> senses glutamate levels (protein breakdown product)
Carbohydrate induced hyperammonemia
Citrin deficiency
- High protein, low carb diet
hyperammonemia, diarrhea, PTT, pneumonitis
PAA: Low arginine, ornithine, lysine
UAA: high arginine, ornithine, lysine
- high LDH/ferritin
LPI
SLC7A7 - dibasic AA transporter
+ macrophage activation syndrome
What is the name for organic acids with the following C chain lengths:
2, 3, 4, 5, 6
2 - acetic
3 - propionic
4 - butyric
5 - valeric
6 - caproic
What is the name for dicarboxylic organic acids with the following C chain lengths:
2, 3, 4, 5, 6
2 - oxalic
3 - malonic
4- succinic
5- glutaric
6 - adipic
what is the cofactor used by enzyme that causes PA?
Biotin
PA = propionyl-CoA carboxylase deficiency
C5DC
Glutarylcarnitine
- GA1
C5
Isovalerocarnitine
IVA
Boiled cabbage odor
Tyrosinemia type I
FAH deficiency
Treatment for ALD7A1 (antiquitin) deficiency
Pyrodoxine 5 Phosphate
B6 dependent epilepsy
methylcitric acid
MMA or PA
methylcrotonylglycine
3MCC
Also seen in multiple carboxylase deficiency
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Tiglylglycine
PA, HSD10, 3-ketothiolase
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Most common cause of adipic acid elevation
Jello
Alanine/lysine > 3.0
mitochondrial dysfunction
3-hydroxy-3-methylglutaric acid
HMG-CoA Lyase deficiency
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2-keto-isovaleric and 2 hydroxy-isovaleric acid
MSUD
- 2-keto acids = MSUD
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3-methylglutaconic acid
HMG-CoA lyase deficiency
Barth syndrome + other mito membranse disorders
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methylsuccinic acid
Ethylmalonic encephalopathy
very high ethylmalonic and adipic acid in urine
Ethylmalonic aciduria
5-oxoproline
Glutathione synthetase deficiency
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4-OH-butyric acid
Succinic semialdehyde dehydrogenase deficiency (SSADH)
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4-hydroxycyclohexylacetic acid
Hawkinsonuria - 4OHphenylpyruvate dioxygenase deficiency
- metabolic acidosis + tyrosinemia
- Resolve in first year of life
What is C5OH?
Hydroxyisovaleryl-CoA
- B-ketothiolase
- HMC-CoA Lyase
- 3MCC
- Multiple carboxylase deficiency
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C4DC
C4DC = succinyl-CoA
- SUCLA2 (Succinyl-CoA synthetase) deficiency
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Postprandial hypoglycemia
Hyperinsulinism or HFI
Hypoglycemia after 3-12hr fast
Glycogen or gluconeogenesis defect
Hypoglycemia after 12 hour fast
FAO defect (low ketones) or ketotic hypoglycemia
GSDs that predominant present as liver disease (without hypoglycemia)
Type IV (Branching enzyme)
Type VI (liver phsophorylase/phosphorylase kinase)
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GALT Q188R
Classical galactosemia, caucasians
GALT S135L
Classic galactosemia, African Americans
GALT N314D
Duarte variant
GALT K285N
Variant galactosemia
Adolase B deficiency
HFI
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How to tell apart SBCAD from Ethylmalonic encephalopathy?
SBCAD: EMA, methylsuccinic acid, C4
ETHE: EMA, adipic acid, C4
What does ACAD9 cause?
mito complex I deficiency
- Cardiomyopathy, neuro, muscle
- May have signs of FAOD and liver failure
Bulbar palsy, optic atrophy, SNHL, neuropathy, respiratory failure
Brown-Vialetto-Van Laere syndrome
Most common Riboflavin transporter defect
SLC42A3
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Name 4 glucose transporters
SGLT1 - Glu+Galactose malabsorption -> profuse diarrhea
SGLT2 - renal glucosuria
GLUT1 - epilepsy
GLUT2 - fanconi bickel (GSD like)
Hyperammonemia, hypoglycemia requiring high GIR
Glutamate Dehydrogenase (GDH)
- Hyperinsulinism + hyperammonemia
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FAOD with hyperinsulinism
SCHAD
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What biochemical marker distinguished GSD1 from GSD3?
Lactate. GSD1 is also gluconeogenesis defect so lactate elevated when fasting; this is not true in GSD3
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What metabolites tell you NAPH/NAD+ in mitochondria?
3OH-butyrate/Acetoacetate
Lactate/pyruvate = cytoplasmic
High lactate/pyruvate
Low 3OH Butryate/acetoacetate
Pyruvate carboxylase deficiency
Disconnect between mito and cytoplasmic NADH/NAD+ (redox) state
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Lactic acidosis with low lactate/pyruvate ratio (<12)
Secondary lactic acidemia
Pyruvate dehydrogenase (Pyruvate high)
Pyruvate transporter
Thiamine deficiency (PDH affected)
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Lactic acidosis during fasting
Gluconeogenesis (FBPase or G6Pase - GSD1)
FAOD (secondary gluconeogenesis impariment)
Postprantial lactic acidosis
Inability to store glucose -> GSD0, GSDIII, GSD VI
Glucose metabolism -> PDH, Pyruvate transporter (normal L/P ratio)
-> PC, ETC disease (high L/P)
Postprantial lactic acidosis and ketosis
high L/P ratio
Hyperammonemia with low glutamine
High citrulline, proline, lysine
Pyruvate Carboxylase
Postprandial ketosis since TCA cycle slowed and acetoacetate is used to synthesize ketones instead
- Low spartate production -> Urea cycle block
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Fasting ketotic hypoglycemia + high postprandial lactate
GSD0 or GSD3
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LSD due to protein associated with autophagolysoomal fusion/pH control
Neuronal Ceroid Lipofuscinoses
LSD due to cholesterol binding protein
NPC2
sebelipase alfa
ERT for Wolman/cholesterol ester storage disease
sebelipase
Alglucosidase alfa
ERT for pompe
alglucosidase
Imiglucerase, Velaglucerase, Taliglucerase
ERT for Gaucher (glucocerebrosidase)
- glucerase
agalsidase
ERT for fabry (alpha galactosidase)
agalsidase
PEX7
RCDP type 1 (low plasmalogen)
- Type 1 also high phytanic acid
NBS for C5OH
BCAA pathway intermeidates (Leu and Ile)
+ holocarboxylase and HMG-Coa Lyase
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alpha aminoadipic aciduria
COOH-CH(NH2)3-COOH
Lysine/tryptophan breakdown intermediate; metabolized to acetoacetylcoa via glutaryl coa
- DD/ acidosis vs non-disease
treatment for OAT
Pyridoxine, arginine restriction
low homocysteine, high methionine
MAT - benign vs CNS
GNMT (methyltransferase) - hepatomegaly, high LFTs
SAHH, AHCY (Adenosylhomocysteinase) - MR, FTT
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4-OH Phentyllactic, 4OH-phentylpyruvic, and 4OH phenylacetic acid
Tyrosinemia - 4OH phenyl-acids elevated in all three types
TAT, 4HPPD, FAH
4OH phenyl acids + 2-L-cystein-S-yl-1,4-dihydroxycyclhex-5-en-1-yl acetic acid
2-L-cystein-S-yl-1,4-dihydroxycyclhex-5-en-1-yl acetic acid = Hawkinsin
4-hydroxyphenylpyruvate dioxygenase deficiency
Normal -> metabolic acidosis + FTT
BH4 defects with high Phe
PTPS, PCD, DHPR
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BH4 defect wiht high primapterin
PCD
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BH4 defect with high biopterin
DHPR
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high 3OMD
AADC
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High HVA
Dopamine B Hydroxylase Def
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PAA profile for SUOX
High taurine, low cystine
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Precursor to sulfur AAs
Methionine
High a-aminoadipic semialdehyde and pipecolic acid
antiquitin
A-aminoadipic semialddehyde dehydrogenase deficinecy
Pyridoxine dependent epilepsy
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High L-Dopa, 3 methoxytyrosine, Thr, Glycine
Low HVA, 5-hydroxyindoleacetic acid
UOA: vanillactate acid
PNPO
Pyridoxal-5-phosphate oxidase deficiency
Pyridocal-phosphate dependent epilepsy + cerebral atrophy
biochem looks like AADC + theronine dehydratase + glycine cleavage sysem)
Butyrylcarnitine
Ethylmalonic acid
SCAD
ACADS gene
Butyrylcarnitine = C4 (ddx isobutyrylcarnitine in IBDH deficiency)
EMA ddx MADD, EE, mito, litchee, jamaican vomiting sickness
Which AAs are NORMAL in urine of Hartnup disease?
SLC6A19 - neutral AA transporter
Glycine, Proline, Hydroxyproline are normal
Urine AA: Cystine, Lysine, ortnithine, argnine
Cystinuria
SLC3A1
-
PAA: Low Lys, Arg, Orn
UAA: High Lys, Arg, Orn
LPI
- cationic transporter SLC7A7
Lys, Arg, Orn
UOA: Thymine and uracil
Dihydropyrimidine dehytogenase deficiency
- 5FU toxicity, MR, microcephaly, FTT
4 OH Butyric acid
Succinic Semialdehyde Dehydrogenase deficiency
ALDH5A1
Succinic semialdehyde cannot be tunred into succinic acid, so becomes 4OHB instead
high erythritol, arabitol, ribitol
Transaldolase
TALDO1
Hydrops vs severe liver disease
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XL Sideroblastic anemia
ALA synthase deficiency
ALAS superactivity = prophyria
Stool isocoproporphyrin
UROD
Porphyria cutaneous tarda or heptoerythropoetic porphyria
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Low serum Cu and Ceruloplasmin, abnormal plasma catecholamines
Menkes (ATP7A)
Low serum Cu and ceruloplasmin, high urinary copper
Wilsons (ATP7B)
Low serum Cu and absent ceruloplasmin, lower iron, high ferritin
Aceruloplasminemia (CP gene)
Brain iron accumulation
petechiae, acrocyanosis, diarrhea, epilepsy, movement d/o
Ethylmalonic encephalopathy
ETHE1
High EMA and Methylsuccinic acid
High C4 and C5
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4 enzymes that require biotin
Pyruvate carboxylase (Mito)
Propionayl-CoA carboxylase (PA)
B-methylcortonyl CoA Carboxylase (3MCC)
Acetyl-CoA Carboxylase
High C5OH, high 3-OH IVA, 3 methylcrotonylglycine, low carnitine
3MCC
- leucine metabolism
4 disorders of Leu breakdown
MSUD
IVA - 3IVA, C5
3MCC - 3MCG, 3IVA, C5OH
3MGC - 3MCG, 3MGA, 3IVA, C5OH, C6DC
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C3 + C4DC
Think MMA/ SUCLA
Lamellar lipoproteins
LCAT
low HDL
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Frederickson Lipid Classification
CLIVE
I - Chylo
II - LDL
III - IDL (VLDL remnant/ B- VLDL)
IV - VLDL
V - Everything else
How do you tell apart abetalipoproteinemia from familial hypobetalipoproteinemia
Carriers for a-beta (MTTP - microsomal TG transfer protein) do NOT have hypobetalipidemia;
hypobetalipoproteinemia (APOB) do have hypobetalipidemia.
acanthocytosis + steatorrhea; low LDL and TG; carriers have low betalipoproteins
Familial hypobetaliporptoteinemia
APOB gene
- Mostly truncating variants
- Unable to form chylomicrons from dietary fats, Vit E absorption
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acanthocytosis + steatorrhea; Low LDL and TG; carriers have normal betalipoproteins
Abetalipoproteinemia
MTTP
- Microsomaltransfer protein
- Carriers have no phenotype
Unablte to form chylomicrons from dietary fat - vitE def
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Low LDL and TG, Apo A1 and ApoB
Lipid laden enterocytes
Chylomicron retention disease
SAR1B -> abnormal trafficking of chylomicrons within enterocytes
Fat malabsorption, FTT, Vit deficiency
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high Chylomicrons, Cholesterol, TG very high
Lipoprotein lipase (LPL) deficiency vs ApoC2
AR, carriers have familial combined hyperlipidemia
- Abd pain/pancreatitis; need low fat diet
- not associated with CAD (hepatic lipase has arteriopathy)
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high ACE, tartrate-resistant acid phosphatase (TRAP), and chitotriosidase
Gaucher
Glucocerebrosidase def
N370S, L444P
high cit, argninine, theronine
High ammonia, galactose, AFP
Citrin deficiency
- supplement argnine/aspartate, high protein diet
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how do you distinguish hypoglycemia caused by hyperinsulinism from FAOD?
Both are non-ketotic
- Free FA high in FAOD
- Free FA (lipolysis) low in hyperinsulin
Mousy odor
PKU
High ammonia, normal citrulline, high lactate
Pyruvate carboxylase
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Ways to distinguish GSDI from other GSDs
High uric acid and lactic acid in GSD1
Moderate ketosis in GSDI - higher ketones in GSD0, III, IV, and IX
Nephromegaly most prominent in GSD1
Transient LFTs in GSD1 - Cirrhosis in GSD IV
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GSDs with postprandial hyperglycemia
GSD0
Fanconi-Bickel
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GSDs with normal lactate
GSD III
Only elevated postprandially in GSD VI and GSD IX
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Jaundice, hepatosplenomegaly, lymphadenopathy, anemia
Mevalonic Aciduria
MVK deficiency (Pre-squalene)
- alleleic with hyper IgD
+ DD
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Male cat urine smell
3-OH IVA
3MCC, multiple carboxylase deficiency
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Rancid butter smell
Tyrosinemia type 1
- Also cabbage
Sulfur smell in urine
Cystinuria and Tyr type 1 (methionine)
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high alk phos -> IEMs
bile acid synthesis disorders, GPI anchor disorders
IEMs with hypothyroidism
Mito, CDG, TFP
MMA vs PA
PA has more cardiomyopathy
MMA has more renal
NBS: high C5
IVA vs enthylmalonic encephalopathy vs SBCAD (non disease)
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etheylmalonic acid + butyrylcarnitine, butyrylglycine
SCAD
methylacritic acid
hydratase or 2-hydroxyisubtyryl-Coa Hydrolase deficiency
Val/Ile metabolism
Neuro + cardiomyopathy + hepatomegaly
Hydratase (ECHS1) - 2-methyl-2,3-dihydroxybutryate, C4
HIBCH - C4OH (hydrolase deficiency)
MMA + 3OH-isobutyric acid
MMA semialdehyde dehydrogenase
ALDH6A1
- Val metabolism
- non-disease (found on NBS)
Hydroxyphntylpyruvate dioxygenase
HPD -> Tyr type 3 or Hawkinsonuria (c.722A>G)
- benign
Isolated hypermethionine
Mudd’s disease
MAT
- Cabbage odor
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which methionine -> hcy disorder does not have ID
MAT and GNMT
SAMH and ADK have ID
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urine uroporphyrin, tool isocoproporphyrin
Porphyria Cutanea Tarda
disorders treatable with uridine supplement
Proximal pyrimidine synthesis
UMPS, DHODH, CAD
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HEXA R247W (739 C>T), R249W (745 C>T)
Tay Sachs peudodeficiency alleles
SUMF1
Multiple sulfatase defiency
MLD + MPS + ichthyosis
C5OH + C6DC
HMG-CoA Lyase
C5OH and C5:1
Beta Keto Thiolase
Hydrops with MPS
MPS 7 -> sly
What metabolite do you need HPLC to see
Homocitrulline
LSD with interstitial lung disease
NP - B (acid sphingomyelinase)
HSM + HLH
LPI
High Orn, Arg, Lys
HSM + hemolytic anemia
Transaldolase
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HSM + recurrent inflammation
MVK