SMPD1 and anterior segment dysgenesis: The numerous sequence variants in the SMPD1 gene and variability in residual ASM activity, as well as other genetic and epigenetic factors, result in a spectrum of ASMD disease severity from a uniformly fatal form with death by 3–4 years of age (infantile neurovisceral ASMD type A, Niemann-Pick Disease [NPD] type A) [3]), to chronic forms characterized by visceral disease [4].