Seven novel mutations of the SMPD1 gene in four Chinese patients with Niemann-Pick disease type A and prenatal diagnosis for four fetuses

Background: Niemann-Pick disease type A (NPD-A) is a rare autosomal recessive lysosomal storage disorder caused by acid sphingomyelinase deficiency. Only a few cases have been documented in mainland China, and prenatal diagnosis has not been performed to date. In this study, the clinical and laboratory features of four Chinese patients with early-onset NPD-A were summarized.

Methods: Four patients with NPD-A were the firstborns of non-consanguineous parents from four unrelated Chinese families. Bone marrow analysis, acid sphingomyelinase assay and genetic studies were performed. SMPD1 gene studies on amniocytes were performed for the prenatal diagnosis of four fetuses from three families.

Results: Four patients were admitted at the age of 1-10 months due to jaundice, hepatosplenomegaly and psychomotor retardation. Liver histopathological analysis revealed glucolipid accumulation. Massive foamy histiocytes were found in the bone marrow. Acid sphingomyelinase activities of peripheral blood leukocytes were significantly decreased (4.05-21.9 nmol/h/mg protein, normal range 216.1-950.9 nmol/h/mg protein). Seven novel mutations (c.518-519insT, c.562_563insC, c.792Gdel, c.949G>A, c.1487_1499delACCGTGTGTACCA, c.1495T>C and c.1670T>C) of the SMPD1 gene were identified in four patients. Only one fetus had two mutations of the SMPD1 gene of amniocytes. The results suggested that the fetus was affected by NPD-A. The mother chose artificial abortion. The other three fetuses were not affected by NPD-A. No mutation of the SMPD1 gene was detected in the cultured amniocytes from the mothers. Postnatal genetic analysis and normal development of the three infants confirmed the prenatal diagnosis.

Conclusions: Seven novel mutations associated with NPD-A were identified in the Chinese population. Prenatal diagnosis for four fetuses of three families was successfully performed by amniocyte gene analysis.