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Syndromes > Biochemistry + metabolic syndromes > Flashcards

Biochemistry + metabolic syndromes Flashcards

1
Q

6 symptoms that prompt consideration of a metabolic disorder

A

Catastrophic neonatal presentation
Biochemical disturbances
Liver disease or dysfunction
Neurologic features (delay, ataxia, stroke)
Myopathy or cardiomyopathy (heart, skeletal)
Signs of a storage disease

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2
Q

cause of rapid breathing (tachypnea) in neonate

A

This info is inaccurate, skip. (Bc acidosis = compensatory alkalosis.)

could be due to trying to lower acidity of blood by exhaling carbon dioxide due to LACTIC ACIDOSIS

could also be due to high ammonia levels.

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3
Q

HCO3 - bicarbonate level - becomes low: when?

A

due to metabolic acidosis.

in organic acidemia - too much acid - body attempt to buffer it by producing more buffer to neutralize acid - HCO3 - as result, HCO3 level drops = metabolic acidosis.

To compensate for acid, body breathes more to release CO2, which makes blood more basic. (respiratory alkalosis) –> LOW CO2. Low pH.

Organic acidemias = LOW pH [acidic]
Urea cycle disorders = HIGH pH

pH tells you what happened first. If pH is low, then it started with metabolic acidosis. If pH high, more likely due to ammonia. Ammonia makes person breathe more rapidly. This decreases CO2. Makes blood more alkaline. pH is thus increased.

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4
Q

Urea cycle disorders
and
Organic Acidemias
… can present with:

A 
CHRONIC SYMPTOMS
aversion to protein
Poor feeding, anorexia
Vomiting
\+/- Hypotonia
\+/- Develop delays

CRISIS SYMPTOMS:
vomiting/seizures
ALKALOSIS if organic acidemia (compensatory)
ACIDOSIS if Urea/Ammonia

…if more distal defect in cycle, can present with liver enlargement/dysfunction, or dev delays, without crises

metabolic acidosis
hyperammonemia (high ammonia)
hypoglycemia
episodes of biochemical decompensation (”metabolic crises”)

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5
Q

organic acid is what’s left after de-amination of

A

amino acids (removal of N group –> to urea cycle)

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6
Q

developmental delay, hypotonia, ocassional seizures if sick - which test to order?

A

plasma/urine amino acids to test for urea cycle disorder, esp during “crises”

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7
Q

Organic Acidemia - Biotinidase deficiency

A

hypotonia, seizures
eczema, alopecia
hearing loss, retinal disease

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8
Q

which conditions require testing of urine organic acids?

A

organic acidemias,
fatty acid oxidation defects,
mitochondrial disorders

during periods of decompensation (crises) - otherwise may be uninformative.

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9
Q

renal fanconi syndrome

A

severe metabolic liver disease,
kidney disease

kidneys not working properly
can’t retain bicarb, glucose, amino acids, phosphate
pH low/acidic

(low phosphate causes rickets)

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10
Q

fatty acid oxidation defect - blood findings?

A 
low glucose (incidental)
LOW KETONES

ketones –> should be high if glucose is low, to compensat,e but low ketones could mean a defect in fatty acid oxidation.

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11
Q

tyrosinemia associated with symptoms of ____, another genetic condition

A

porphyria - usually young/adult women
—> neurologic crises

can be seen in Tyrosinemia Type 1 due to succinyl acetae

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12
Q

acute fatty liver could mean……

A

METABOLIC CRISIS

      how:
kid doesn't want to eat because sick
fat goes to liver to be broken down
but fat can't be broken down due to defect
thus, liver becomes fatty
 due to: “Reye syndrome-like disease” fatty acid oxidation defects mitochondrial disease
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13
Q

homocysteinuria

A 
SKELETAL
Unusually tall
Long limbs/ arachnodactyly
Pectus excavatum/ carinatum
Osteoporosis
Scoliosis
Pes cavus

NEURO
delay/MR
psychiatric
seizures

EYE
myopia, lens dislocation

BLOOD
tendency to clot

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14
Q

Homocysteinuria VS Marfan - 3 differences

A

Homocyst. vs Marfan
stiff joints / loose joints
clotter / aortic dissection
dev delay/MR / no mental issues

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15
Q

Menke

A

Metabolic disease of copper

hypopigmentation
kinky hair
hypotonia, delays
death

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16
Q

Pompe

A

Glycogen build-up; recessive

acid alpha-glucosidase (also known as acid maltase) -GAA gene –> glycogen builds up in lysosomes

hypotonia
HCM or cardiomegaly
hepatomegaly

Myozyme

1 in 40,000

17
Q

Lesch-Nyan

A

build-up of uric acid

Developmental delays, learning disorder
Insensitivity to pain; 
	self-injurious behavior
Renal stones (uric acid)
Hyperuricemia

XLR; 1 in 380,000

18
Q

Zellweger

A 
Prenatal onset
Dysmorphic
Hypotonia
Seizures
Liver disease
Death within months

peroxisome
autosomal recessive
many genes can cause it

19
Q

heart and muscle mainly use __ fat, so __ fatty oxidation disorders affect the heart and muscle, primarily.

A

heart and muscle use LONG CHAIN FATS…

so cardiomyopathy and myopathy mostly present in longer chain fatty acid disorders because the long chain fats aren’t cleaved and barely any ketones are generated.

20
Q

low ketone production found in which disorders?

A

Long-chain fatty acid oxidation
Medium-chain fatty acid oxidation
Carnitine transport (of fatty acids into mitochondria)

21
Q

ketosis associated with which disorders?

A

short chain fatty acid oxidation (cleave lots of ketones from a long-chain fatty acid, to medium-chain, but issue at short chain).

22
Q

low free carnitine is indicative of -

A

Total carnitine = free carnitine + esterified carnitine.
Free carnitine = 70-90% of total carnitine.

To evaluate carnitine transport defects, fatty acid oxidation defects, organic acidemias, mitochondrial disease.

If healthy/asymptomatic, low free (and high esterified) carnitine levels may indicate an unusual compound binding to free carnitine.

23
Q

diagnostic tests for fatty acid oxidation disorders, organic acidemias

A

organic acids

free carnitine/esterified carnitine. if + then:

ACYLCARNITINE
ACYLGLYCINE – stuff that binds to stuff
certain metabolites bind to carnitine/glycine; can be diagnostic. check blood, esp when sick.

24
Q

Ragged Red Fibers

A

MELAS

NERP (?)

25
Q

if lethargy, test:

A

ammonia

(urea cycle defects
certain amino acid disorders
organic acidemias
fatty acid oxidation defects
mitochondrial disorders)
26
Q

Recurrent acute decompensation - what to order?

A 
Blood gases
Electrolytes, bicarbonate
Glucose
Ammonia
Liver functions
Lactate
Urinalysis
----------------------------------------
if suspicion is high:
    Blood amino acids
    Blood acylcarnitines
    Urine organic acids
    Urine acylglycines
27
Q

NTBC is tx for which metabolic condition?

A

Tyrosinemia type 1 – prevents conversion of a substance metabolically upstream of tyrosine

28
Q

meconium ileus

A

pretty much diagnostic of CF

29
Q

Class 1, 2, 3 mutations - severity?
Class 4, 5 mutatoins - severity?
DF508 - which class?

A

df508 = class 2

class 1,2,3 = severe
class 4,5 = less severe

class 1 = null

30
Q

congenital bilateral absence of vas deferens / male infertility

A

screen for uncommon CF mutations

males usually have normal sweat test and lung function, but maybe asthma. large proportion of people with this abnormality have CF mutations.

31
Q

what modifies CF severity?

A

Intron 8 polypyrimidine tract (T) dictates splicing efficiency of CFTR

5T – least efficient
7T
9T – most efficient

in df508, skew toward 9T (100%) vs wt (11%)

32
Q

CF - which chronic/complex disease is increased in individuals with CF?

A

diabetes, 50% risk after age 20

33
Q

lung function in CF primarily correlates with

A

nutritional status. CF is primarily a nutritional disease

34
Q

If person has severe CF mutation + 5T / wt allele, are they affected? what about 9T?

A

9T + severe = unaffected (“efficient gene splicing)

5T + severe = CAVD (vas def) in males (“inefficient splicing”)

35
Q

Effect of Intron 8 on Mild CFTR mutations (such as R117H)

Genotype mild mutation/severe mutation

A

Mild mutation with 9T –> CBAVD

Mild mutation with 5T –> Pancreatic Sufficient CF

36
Q

CF incidence

    • caucasians
    • african americans
    • Hispanics
A
    • caucasians / 1 in 3,000 // carrier 1/30
    • african americans / 1 in 17,000 // carrier 1/65
    • Hispanics / 1 in 10,000 // carrier 1/50 (!)

asians lower.

Syndromes (3 decks)

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