inborn errors of metabolism Flashcards
deficiency in pku
phenylalanine transferase (cant convert phe to tyrosine); mild problem with BH4
lab results for pku
UOA: inc phenylketones
PAA: inc Phe, low tyrosine
due to low tyrosine-
1. low neurotransmitters: dopamine, norepinephrine, and adrenaline
2. fair skin (Tyr is a precursor of the skin pigment melanin)
PKU as teratogen (features)
dysmorphic features, microcephaly, IUGR, congenital heart
clinical features in infant with PKU
fair skin
eczematoid rash
mousy/musty odor
treatment of PKU
restrict phe, BH4 supplement
first test for change in mental status
blood glucose
condition could falsely elevate NH4
use torniquet, prolonged process in lab (result in 1 hr), no ice
how to collect NH4
free flow, ice, process within 1 hr
Condition with elevated lactate:pyruvate
mitochondrial d/o
What presents with elevated plasma AA
aminoacidopathies, urea cycle, organic acedemia
What presents with abnormal urine organic acid
AA, FAOD, organic acid
Mode of inheritance of aminoacidopathies
autosomal recessive
Labs suggestive urea cycle do
AbN PAA, elevated NH4, respiratory alkalosis
Labs suggestive Organic Acids
Abn PAA, metabolic acidosis, AbN UOAs
Deficiency in MSUD
branched chain alpha ketoacid dehydrogenase
What are the Branched-chain AA
Isoleucine, valine, LEUCINE
MSUD and ethnic group
Old order Mennonites
presentation MSUD
diminished arousal
poor feeding
hypertonia
coma
death
maple syrup smell
which branched-chain AA causes Sx in MSUD
Leucine (neurotoxic and osmotic effect)
Acute mgt of MSUD
high dextrose isotonic Iv and lipids; serum Na high normal
long term mgt for MSUD
diet, liver transplant
deficiency in homocystinuria
cystathionine beta synthetase
labs finding homocystinuria
elevated homocysteine and methionine in blood, urine, NBS, plasma AA
clincal features of homocystinuria
intellectual disability
tall stature
osteoporosis
recurrent thrombosis
ectopia lentis (lens dislocation- downwards)
differential for homocystinuria
marfans
Management of homocystinuria
vit B6 (cofactor)
betaine (dec homocysteine in bld)
aspirin (prevent stroke)
deficiency in tyrosinemia (hepatorenal tyrosinemia)
fumarylacetoacetase
pathognomonic tyrosinemia
inc tyrosine (lacks specificity and sensitivity) must differentiate from transient tyrosinemia of newborn
inc urine and bld succinyl acetone
Confirmation tyrosinemia
UOA: succinylacetone
PAA inc tyrosine and methionine (liver issue)
Treatment tyrosinemia
Nitisinone, tyrosine restrict
Deficiency Hyperglycinemia (nonketotic hyperglycinemia)
deficiency in glycine cleavage
lab and clinical findings in hyperglycinemia
inc CSF glycine
seizure
hiccups
apnea
Absent corpus collosum
EEG burst supression
urea cycle
A- N-acetylglutamate synthetase
B- Carbamyl phosphate synthetase
C- Ornithine carbamyl transferase
D- Arginosuccinic acid synthetase
E- Argininosiccinic lyase
F- Arginase
findings in urea cycle oct def
high: glutamine, orotic acid
low: citrulline, arginine
urea cycle def arginosuccinic acid synthetase
high: glutamine, orotic acid, citrulline low: arginine
urea cycle arginase def
cant change arginine last step- all high: glutamine, orotic acid, citrulline, arginine
Which inborn metab defect is X-linked recessive
OCT (ornithine carbamyl transferase)
Treatment to remove ammonia
- hemodialysis (fastest)
- Hydration
- Remove nitrogen: sodium benzoate and sodium phenylacetate- scavenger, water soluble
- Sodium phenylbutyrate- once stable
What to monitor when treating with Benzoate for NH4
Na and Cl
(high Na content, hence improtance of hydration)
What affects outcome for urea cycle DO
length of time with high NH4
Outcome/Risk for arginase deficiency
Spastic diplegia
What is organic acids
deaminated remains of amino acids