[A case of a Korean adult affected by type B Niemann-Pick disease: secondary sea-blue histiocytosis and molecular characterization].

Niemann-Pick disease (NPD) is an inherited metabolic disorder caused by a deficiency of the enzyme acid sphingomyelinase coded by SMPD1 gene. In contrast with type A NPD, a severe neurodegenerative disease of infancy, type B NPD patients have little or no neurodegeneration, and frequently survive into adulthood. Although over 100 mutations have been found within the SMPD1 gene causing NPD, there was only one report about SMPD1 mutation status of a Korean NPD patient. We report a case of a 32-yr-old female, who presented with thrombocytopenia without any neurologic involvement. Hepatosplenomegaly was detected by both physical examination and imaging studies, and a thoracic radiograph examination showed a pattern of interstitial lung disease. Biochemical tests revealed increased liver enzymes, cholesterol, triglyceride, and LDL-cholesterol, and decreased HDL-cholesterol. Sea-blue or foamy vacuolated histiocytes occurred in bone marrow and liver. Sequencing analysis of SMPD1 using genomic DNA from peripheral leukocytes identified a compound heterozygote of two mutations at exon 2: p.E246K and p.A357V. The former is a known mutation in an Italian patient, and the latter has not been reported yet. She has received oral rosuvastatin to treat hyperlipidemia at a dose of 10 mg per day for 4 months. This is the second report in which the mutation of SMPD1 gene was detected in a Korean NPD patient. The active genetic analysis of SMPD1 gene in patients with typical findings of type B NPD would enable us to facilitate diagnosis as well as to accumulate data on molecular characteristics of Korean NPD patients.