10/13 B-Oxidation Disorders

Question 1

infantile onset OTC deficiency

Answer 1

x-linked
males severely affected (little to no enzyme activity)

female presentation dependant upon X-inactivation

vv low citrulline

Question 2

adult onset OTC deficiency

Answer 2

more likely for females, may present w/ stress or pregnancy

normal citrulline

Question 3

lab values OTC deficiency (all ages)

Answer 3

respiratory alkalosis
high ammonia
low BUN (defect is in prod of urea)
high plasma glutamine (important for Dx and prognosis, observed to be vv high in fatal cases)
v high orotic acid in urine

Question 4

OTC deficiency presentation/Tx

Answer 4

rapid drop in neurological status (due to ammonia crossing BBB)
Tx: sodium benzonate (nitrogen scavengar), dialysis, fluids

Question 5

lab values/genetic testing MCAD deficiency

Answer 5

elevated acylcarnitine profile (should be metabolized by MCAD)
newborn screening shows high FA profile
genetics: ACADM 985A>G homozygous most common

Question 6

MCAD deficiency presentation

Answer 6

extreme sleepiness, behavior changes
cardiomegaly/cardiac failure
fever, decreased appetite
fasting –> episodic hypoglycemia and hypoketosis, vomiting, acidosis, coma