NCIt definition : An autosomal recessive lysosomal storage disease caused by mutations in the SMPD1
gene, encoding sphingomyelin phosphodiesterase. The condition is characterized by
hepatosplenomegaly and interstitial lung disease, but with little neurological involvement.
It is part of a continuum of disease resulting from decrease activity of sphingomyelin
phosphodiesterase, with Type B being the milder form.;