mcq

Question . 1. A blonde, blue-eyed girl was admitted at 2.5 mo of age with severe

emesis to rule out pyloric stenosis. She had poor development, eczema, and a

musty odor. The most likely diagnosis is:

Wiskott-Aldrich syndrome

Galactosemia

Cystinosis

Phenylketonuria

Explanation: This is a classic picture of phenylketonuria

(PKU). Fair complexion, eczema, emesis, and mental

retardation are common features. The musty-mousy odor is

phenylacetate, a metabolic by-product of the blocked pathway

due to deficiency of phenylalanine hydroxylase. (See Chapter

74 in Nelson Textbook of Pediatrics, 17th edition.)

Biotinidase deficiency

Question . 2. The child described in Question 1 survives to adulthood and becomes

pregnant. Risk to her fetus if her diet is poorly controlled include all of the following

except:

Microcephaly

Congenital heart disease

Mental retardation

Cataracts

Explanation: Adults who have the autosomal recessive

disease PKU are at risk for mild to moderate neurointellectual

problems if they are on an unrestricted diet. If a woman with

poorly controlled PKU becomes pregnant, her high

phenylalanine levels will be reflected in the fetus, who is at risk

for congenital heart disease, microcephaly, and developmental

delay. The baby will also be a carrier. (See Chapter 74 in

Nelson Textbook of Pediatrics, 17th edition.)