Correction of enzyme levels with allogeneic hematopoeitic progenitor cell transplantation in Niemann-Pick type B.

Niemann-Pick type B (NP) is an autosomal recessive lysosomal storage disorder with variable phenotypes for which few patients have undergone hematopoietic progenitor cell (HPC) transplantation. We present an 18-month old with NP type B who underwent two allogeneic HPC transplants from her HLA-identical sister. Sphingomyelinase in the peripheral leucocytes and skin fibroblasts was absent at diagnosis. Engraftment failed following initial transplant; therefore a second with the same donor was performed. Engraftment since has been durable; all subsequent sphingomyelinase levels have been normal. Our experience indicates that HPC transplantation for patients with NP type B is feasible and beneficial.