Deck 43: Medical Nutrition Therapy for Genetic Metabolic Disorders

Question 1

Which of the following metabolic disorders is NOT classified as an organic acidemia?

A) Methylmalonic metabolic disorder
B) Propionic metabolic disorder
C) Isovaleric metabolic disorder
D) Argininosuccinic aciduria

Answer 1

D
Explanation: Argininosuccinic aciduria is a urea cycle disorder that results in arginine deficiency. Methylmalonic metabolic disorder and propionic disorder promote the development of metabolic acidosis through the accumulation of organic acids. Isovaleric disorder is also an organic acidemia; however, this disorder can produce metabolic ketoacidosis.

Question 2

Which of the following is the deficient enzyme in glycogen storage disease Ia (GSD Ia)?

A) Glucose-1,6-phosphatase
B) Fructose-1,6-diphosphatase
C) Fructose-1-phosphate aldolase
D) Hexokinase

Answer 2

A
Explanation: GSD Ia involves a defect in the enzyme glucose-1,6-phosphatase. This defect results in impairments in gluconeogenesis and glycogenolysis, which can result in severe hypoglycemia. Fructose-1,6-diphosphatase deficiency is a rare fructose metabolism disorder that promotes metabolic acidosis when fructose is consumed, but fructose levels do not increase in the blood or urine. Hereditary fructose intolerance is associated with a defect in fructose-1-phosphate aldolase that causes a depletion of inorganic phosphate and adenosine triphosphate. This disorder can result in renal and liver damage. Metabolic disorders involving hexokinase have not been identified.

Question 3

The desirable range for blood phenylalanine in a child with PKU is _____ mg/dl.

A) 2 to 6
B) 6 to 10
C) 8 to 12
D) 10 to 20

Answer 3

A
Explanation: Regular checking of blood phenylalanine levels is necessary to monitor for excessive phenylalanine intake and to prevent development of mental retardation. The desirable range for blood phenylalanine concentration is 2 to 6 mg/dl. The diagnosis of PKU is made when phenylalanine levels are greater than 6 to 10 mg/dl. Phenylalanine levels greater than 20 mg/dl are the best predictor of IQ loss.

Question 4

Which of the following is reduced in the diet in the treatment of maple syrup urine disease (MSUD)?

A) Fructose
B) Aromatic amino acids
C) Branched-chain amino acids
D) Sulfur-containing amino acids

Question 5

Which of the following is used in the nutritional management of patients with glycogen storage disease?

A) Oral intake of cornstarch
B) Small, frequent high-protein meals
C) Severe restriction of all carbohydrates
D) Three well-balanced meals a day

Question 6

Which of the following foods would be allowed in the diet of a child with PKU?

A) Peanut butter and jelly sandwich
B) Sugar-free gum
C) Potato chips
D) Spaghetti and meatballs

Question 7

Which of the following metabolic disorders is NOT treated with a low-protein diet?

A) Argininemia
B) Methylmalonic acidemia
C) Ketone use disorder
D) Galactosemia

Question 8

An appropriate description of a metabolic disorder is an autosomal recessive disorder that

A) involves amino acids.
B) results in the reduced activity or absence of a specific enzyme.
C) occurs because the body cannot use dietary amino acids, fatty acids, or monosaccharides.
D) results in the buildup of metabolites in the blood, urine, or both.

Question 9

The current preferred method for screening for inborn errors of metabolism is

A) microarray technology.
B) tandem mass spectrometry.
C) Guthrie bacterial inhibition assay.
D) enzyme-linked immunosorbent assay.

Question 10

Which of the following will NOT result in the development of phenylketonuria?

A) Deficiency in phenylalanine hydroxylase
B) Deficiency in dihydropteridine reductase
C) Insufficient synthesis of biopterin
D) Insufficiency of dietary tyrosine

Question 11

Beyond fatty acid oxidation disorders, which other metabolic disorder is treated with supplemental carnitine?

A) Isovaleric acidemia
B) Ketone utilization disorder
C) Ornithine transcarbamylase deficiency
D) Tyrosinemia

Question 12

Which of the following fruits and vegetables would be allowed in the diet of a person with galactosemia?

A) Bell peppers
B) Watermelon
C) Raisins
D) Tomatoes

Question 13

Which of the following metabolic disorders is NOT a disorder of carbohydrate metabolism?

A) Hereditary glucose intolerance
B) Glycogen storage disease
C) Galactosemia
D) Fructose 1,6-diphosphatase deficiency

Question 14

Which fatty acid oxidation disorder is the most common?

A) Short-chain acyl-CoA dehydrogenase deficiency
B) Medium-chain acyl-CoA dehydrogenase deficiency
C) Long-chain acyl-CoA dehydrogenase deficiency
D) Long-chain 3-hydroxy acyl-CoA dehydrogenase deficiency

Question 15

For infants and children younger than 10 years of age with PKU, which amino acid has to be supplemented in the diet?

A) Cysteine
B) Methionine
C) Phenylalanine
D) Tyrosine

Question 16

The metabolic result that occurs in all of the urea cycle disorders is an accumulation of _____ in the blood.

A) ammonia
B) purines
C) ketones
D) ketoacid

Question 17

Which of the following is NOT one of the possible infant outcomes of PKU mothers with elevated phenylalanine levels?

A) Liver dysfunction
B) Microcephaly
C) Congenital heart disease
D) Low birth weight

Question 18

Which of the following is NOT one of the nutritional treatments that would be provided to patients with metabolic disorders?

A) Restrict the amount of a specific substrate (nutrient) in the diet.
B) Supplement the diet with a greater amount of a "safe" product of metabolism.
C) Replace the defective enzyme through the diet.
D) Supplement the defective enzyme cofactor.

Question 19

Which of the following conversions is defective in galactosemia?

A) Glucose to galactose
B) Galactose to glucose
C) Lactose to galactose
D) Galactose to lactose

Question 20

Which of the following is NOT one of the enzyme deficiencies associated with urea cycle disorders?

A) Ornithine transcarbamylase
B) HMG-CoA reductase
C) Carbamyl-phosphate synthetase
D) Arginase