A 21 year old woman with phenylketonuria discontinued the PKU diet in early adolescence. She presents to her OBGYN for her first prenatal visit. Her husband does not have the disease. Which of the following is the best course of action? A. Since the child is heterozygous for PKU, no special action needs to be taken. B. The patient blood phenylalanine levels should be monitored and appropriate action taken if they become too high. C. The patient should try to avoid excess phenylalanine in her diet by restricting protein intake D. The patient should immediately resume the PKU diet and have her blood phenylalanine levels monitored on a regular basis. D 36 hours after birth, a term male infant presents post seizure. The infant appeared well at birth but on the second day of life developed irritability, vomiting, feed refusal, and becomes increasingly lethargic. Blood gas analysis shows a respiratory alkalosis and plasma ammonia concentrations are found to be 360 micro-m/l (normal for a full term infant is <50 micro-m/l). Which of the following is most consistent with these symptoms? A. Branched-chain alpha-ketoacid dehydrogenase complex deficiency B. Glucose 6-phosphatase deficiency C. Lipoprotein lipase deficiency D. Ornithine transcarbamoylase deficiency E. Phenylalanine hydroxylase deficiency D Which statement regarding phenyketonuria (PKU) is FALSE? A. PKU is the most common disorder of amino acid metabolism in the United States. B. PKU symptoms result from an excess of the essential amino acid, phenylalanine. C. PKU is only caused by a mutation in the gene for phenylalanine hydroxylase. D. A phenylalanine restricted diet must be implemented soon after birth for classic PKU E. Untreated patients with classic PKU will be mentally retarded. C*
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A 21 year old woman with phenylketonuria discontinued the PKU diet in early adolescence. She presents to her
OBGYN for her first prenatal visit. Her husband does not have the disease.
Which of the following is the best course of action?
A. Since the child is heterozygous for PKU, no special action needs to be taken.
B. The patient blood phenylalanine levels should be monitored and appropriate action taken if they become too high.
C. The patient should try to avoid excess phenylalanine in her diet by restricting protein intake
D. The patient should immediately resume the PKU diet and have her blood phenylalanine levels monitored on a
regular basis.
D
36 hours after birth, a term male infant presents post seizure. The infant appeared well at birth but on the second day
of life developed irritability, vomiting, feed refusal, and becomes increasingly lethargic. Blood gas analysis shows a
respiratory alkalosis and plasma ammonia concentrations are found to be 360 micro-m/l (normal for a full term infant
is <50 micro-m/l).
Which of the following is most consistent with these symptoms?
A. Branched-chain alpha-ketoacid dehydrogenase complex deficiency
B. Glucose 6-phosphatase deficiency
C. Lipoprotein lipase deficiency
D. Ornithine transcarbamoylase deficiency
E. Phenylalanine hydroxylase deficiency
D
Which statement regarding phenyketonuria (PKU) is FALSE?
A. PKU is the most common disorder of amino acid metabolism in the United States.
B. PKU symptoms result from an excess of the essential amino acid, phenylalanine.
C. PKU is only caused by a mutation in the gene for phenylalanine hydroxylase.
D. A phenylalanine restricted diet must be implemented soon after birth for classic PKU
E. Untreated patients with classic PKU will be mentally retarded.
C*
Which of the following statements regarding inborn errors of metabolism is FALSE?
A. Often autosomal recessive in inheritance.
B. Can involve synthesis or breakdown of biological compounds.
C. Often result in non-specific symptoms.
D. Accumulation of toxic compounds often contributes to the pathogenesis.
E. Treatment strategy often includes providing patients with the substrate of the deficient enzyme.
E*
A two-week-old infant, who appeared completely normal from birth until that morning, was brought to the
emergency room because of he was unresponsive when his mother tried to feed him. Patient was afebrile. The
patient exhibited metabolic acidosis and urine showed no ketones. Which of the following is the most likely
diagnosis?
A. Biotinidase deficiency
B. Medium chain acyl-CoA dehydrogenase (MCAD) deficiency
C. Maple syrup urine disease
D. Galactosemia
E. Phenylketonuria
B
On her first visit to the pediatrician, an infant is found to have bilateral cataracts. Total galactose level in red blood
cells was elevated. Galactose-1-phosphate level was normal. Which of the following tests will be indicated to assist in
making a diagnosis?
A. Galactose kinase enzyme activity in red blood cells
B. Galactose-1-phosphate uridyl transferase activity in red cells
C. Mutation analysis of the galactose-1-phosphate uridyl transferase gene
D. Tandem mass spectrometry to look for elevated levels of glucose
A
A couple has recently migrated from a rural village in Poland. They have a six- year-old child with mental retardation,
microcephaly, decreased skin and hair pigmentation and a musty odor to the urine. The family history is otherwise
negative. Which of the following is most likely diagnosis for the child?
A. Alkaptonuria
B. Galactosemia
C. Oculocutaneous albinism
D. Phenylketonuria
E. Tyrosinemia
D
Which of the following is not restricted while prescribing dietary therapy for a young infant with phenylketonuria?
A. Breast milk intake
B. Tyrosine intake
C. Phenylalanine intake
D. Protein intake
B
Your patient with phenylketonuria has just announced that she is 18 weeks pregnant. She has been off her
phenylalanine-restricted diet for several years. If she does not make changes to her diet, what is her child most likely
to have?
A. increased tetrahydrobiopterin level
B. low phenylalanine levels due to placental barrier
C. low tyrosine levels due phenylalanine hydroxylase deficiency
D. Microcephaly and probable future cognitive defects
D
A child is referred to you following an abnormal newborn screen that showed elevated medium chain fatty acids.
What should be your recommendation for the care of this infant?
A. avoid carbohydrates
B. feed the child every 3-4 hours
C. prevent intake of carnitine
D. switch to a diet rich in fish oils
E. supplement the diet with tyrosine
B
A 7-day old baby who has been lethargic with poor feeding, poor activity and a weak cry presents to the local
emergency department (ED) where the patient was found to be hypotensive, tachycardic, with poor capillary refill.
Electrolyte panel showed hyponatremia, hypoglycemia, and hyperkalemia. You had the ED nurse call the State
Department of Health for newborn screen results which came back positive for congenital adrenal hyperplasia (CAH).
What is the most likely cause of the CAH?
A. 5 alpha reductase deficiency
B. 11 hydroxylase deficiency
C. 21-hydroxylase deficiency
D. 17,20 lyase deficiency
C
You confirm the diagnosis of CAH and note that the patient has apparent male external genitalia, empty scrotum,
microphallus, and hypospadias on physical exam. Pelvic ultrasound showed normal uterus and ovaries. What would
the chromosome analysis most likely show?
a. 46,XY
b. 46,XX
c. 46,XX/46,XY
d. 45,X/46,XX
B
Which of the following pregnancies is at highest risk to result in a baby with birth defects if no dietary treatment is
implemented during pregnancy?
A. The mother is a dihydrobiopterin deficiency carrier and the father is a PKU carrier.
B. The mother is a PKU carrier and the father is a dihydrobiopterin deficiency carrier.
C. The mother is a PKU carrier and the father is a PKU carrier.
D. The mother is a PKU carrier and the father has PKU.
E. The mother has PKU and the father is a PKU carrier.
E
Defects in which of the following enzyme results in oculocutaneous albinism?
A. Fumaroacetoacetate hydrolase
B. Homogentisic acid oxidase
C. Phenylalanine hydroxylase
D. Tyrosinase
E. Tyrosine hydroxylase
D
Which one of the following is part of the optimal management of a patient with phenylketonuria?
A. A phenylalanine-free diet
B. Diet drinks containing aspartame
C. Medium-chain triglycerides supplementation
D. Overnight nasogastric formula feeding
E. Tyrosine supplementation
A
Which one of the following disorders is a defect in tyrosine metabolism?
A. Albinism
B. Carbamoyl phosphate synthetase deficiency
C. Gout
D. Homocystinuria
E. Methylmalonic acidemia
A
Which one of the following inborn errors of metabolism is not characterized by a typical odor?
A. Alkaptonuria
B. Branched-chain acyl CoA dehydrogenase deficiency
C. Glutaric aciduria type 2
D. Isovaleric acidemia
E. Phenylketonuria
A
A number of genetic diseases can be strongly suspected (no pun intended!) based on the unusual body odor
emanating from the patient when untreated or poorly treated. Which one of the following diseases does not belong
to this group?
A. Cystic fibrosis
B. Diabetic ketoacidosis
C. Isovaleric academia
D. Maple syrup urine disease
E. Phenylketonuria
A
Which one of the following plays a major role in the degradation of long chain fatty acids?
A. The Alanine-Glucose Cycle
B. The Carnitine - Acylcarnitine Cycle
C. The Cori Cycle
D. The Krebs Cycle
E. The Urea Cycle
B
A 9 day old infant presented to the emergency room with recurrent vomiting, hypotonia, respiratory distress and was
found to have profoundly positive anion gap metabolic acidosis and hyperammonemia. Moreover, he emits a strong
sweaty feet odor. Of the following inborn errors of metabolism, which one is the most likely?
A. Diabetic ketoacidosis
B. Isovaleric acidemia
C. Maple syrup urine disease
D. Methylmalonic acidemia
E. Ornithine transcarbamoylase deficiency
B
A poorly-grown 2 month old infant has jaundice, easy bruising, lethargy and decreased consciousness. His laboratory