A 4 year old boy presents to a physician with

neurodegeneration, hepatosplenomegaly and a macular cherry-red spot. The

physician suspects that the most likely underlying cause of these symptoms is

Niemann-Pick disease and she refers the child to a clinical geneticist. In

order to confirm the diagnosis, the clinical geneticist requests DNA sequencing

of the gene which encodes the enzyme which is defective in Niemann-Pick

disease.