Niemann–Pick disease type A, A/B and B (acid sphingomyelinase deficiency). Literature review and clinical observations

Niemann–Pick disease type A, A/B and B (acid sphingomyelinase deficiency (ASD)) is a multisystem and multiorgan disease from the group of lysosomal storage diseases caused by the accumulation of sphingomyelin in various organs and tissues as a result of a mutation in the sphingomyelin phosphodiesterase 1 (SMPD1) gene encoding the enzyme acidic sphingomyelinase (ASM). DCSM is classified as a pan-ethnic progressive and potentially life-limiting metabolic disease and has an autosomal recessive type of inheritance. Reduced activity of DCSM leads to progressive accumulation of sphingomyelin in organs of the reticuloendothelial system – liver, spleen, but can also affect other organs. Clinical manifestations and life expectancy of patients with DCSM differ significantly depending on the subtype of the disease: pediatric (infantile) neurovisceral – type A, chronic neurovisceral – type A/B (intermediate) and chronic visceral – type B. Diagnosis of DCSM is based on the assessment of clinical symptoms, the results of laboratory, instrumental, and molecular genetic methods. As a pathogenetic treatment of Niemann–Pick disease types A/B and B, enzyme replacement therapy with olipudase alfa has been developed. Clinical cases of 8 children with DCSM, observed for 10 years, are presented. The diagnosis was established on the basis of characteristic clinical picture, laboratory and instrumental examination data, confirmed by the results of enzymodiagnostics and molecular genetic study. Of the observed children, there was 1 child with Niemann–Pick disease type A, 2 patients with Niemann–Pick disease type A/B, and 5 children with Niemann–Pick disease type B. Key words: lysosomal storage diseases, Niemann–Pick disease, acid sphingomyelinase deficiency, hepatosplenomegaly, differential diagnosis, children