Lin N, Zhang H, Qiu W et al.
Shanghai Jiao Tong University, Shanghai, People’s Republic of China.
J Lipid Res 2014;55:338–43.
Editor’s note: Niemann–Pick disease (NPD) types A and B are caused by a deficiency in acid sphingomyelinase (ASMase), an enzyme involved in the breakdown of lipids. In healthy individuals, one of the targets of this enzyme is cholesterol, which is oxidized to form 7-ketocholesterol (7-KC). The current authors developed a rapid method of measuring the plasma levels of 7-KC, which they hypothesized to be reduced in patients who were deficient in ASMase, using liquid chromatography–tandem mass spectrometry.
The technique was performed using plasma samples from a number of individuals, including those with ASMase-deficient NPD, unaffected carriers of the disease, patients with other lysosomal storage diseases, and healthy controls. Significantly higher levels of 7-KC were found in patients with ASMase-deficient NPD, as well as in patients with NPD type C (NPC), compared with all of the other individuals, including heterozygous carriers of the ASMase mutation. The authors conclude that this technique is the first simple, quantitative, and sensitive method for the detection of ASMase-deficient NPD, and possibly also NPC.