Niemann-Pick disease, a lysosomal storage disease, is an autosomal recessive condition caused by sphingomyelin phosphodiesterase (acid sphingomyelinase) deficiency resulting in progressive accumulation of sphingomyelin in the lysosomes. Niemann-Pick disease represents a continuous clinical spectrum: Niemann-Pick type A (NPA) typically manifests during infancy with progressive involvement of the central nervous system (CNS) and other organs associated with early death. Specific symptoms include persistent early jaundice, hepatosplenomegaly, growth retardation, developmental delay/intellectual disability, muscular hypotonia, rigidity, cherry red spots, corneal opacities, and discoloration of the anterior lens capsule. There is a higher prevalence of Niemann-Pick type A in the Ashkenazi Jewish population. Type B (NPB) is of later onset and mainly affects visceral organs and lungs with individuals typically surviving into adulthood. Â Niemann Pick type B occurs mostly in Turkish, Arabic, and northern African populations. This laboratory performs Sanger sequencing of the SMPD1 gene.