Question 29

Question:

A 6 month-old girl is brought in by her mother who has noted a protruding abdomen, irritability, and recent inability to lift her head unassisted. Examination reveals a healthy appearing girl with a distended abdomen and cervical lymphadenopathy. Fundoscopy reveals a cherry red macula. Which of the following is the best diagnosis?

Correct Answer: E.  Sphingomyelinase deficiency

This child is presenting with Niemann-Pick’s disease, characterized by irritability, regression of developmental milestones, hepatosplenomegaly, lymphadenopathy, and a cherry red macula.
Glucocerebrosidase deficiency (choice A) causes Gaucher’s disease, which is not associated with a cherry red macula.
Hexosaminidase A deficiency (choice B) is responsible for Tay-Sachs disease, which is similar to Niemann-Pick’s disease down to the cherry red macula. However, Tay-Sachs disease does not feature hepatosplenomegaly or lymphadenopathy.
Iduronate-2-sulfatase (choice C) and iduronidase (choice D) deficiencies cause Hunter’s and Hurler’s syndromes, respectively, and are characterized by facial coarsening. Hunter’s syndrome commonly involves corneal clouding. Neither involve a cherry red macula.