Niemann-Pickrsquo;s disease (NPD) is an inherited metabolic disease caused by the deposition of sphingomyelin and cholesterol in various organs of the body. The disease was first reported by Niemann in 1914 as the first case, and in 1922 Pick described in detail what was seen on pathological examination, hence the name. Two cases were first reported in China in 1963, and individual cases have been reported since then. What causes Niemann-Pick disease? I. Pathogenesis Autosomal recessive inheritance. The disease is autosomal recessive and is more prevalent in Jews. It has been confirmed that types A and B of the disease are caused by deficiency of sphingomyelinase. The enzyme is widely present in the lysosomes of many tissues and is also found in mitochondria and microsomes, especially in hepatocytes. Sphingolipids are found in the cell membrane and subcellular plasma membrane of all cells, including the stroma of erythrocytes. In the absence of this enzyme, these lipids cannot be hydrolyzed, resulting in a large accumulation in the cells, often accompanied by deposition of cholesterol and bisphosphonates. The rationale for the increase in cholesterol is unclear, but there appears to be a close relationship between cholesterol and sphingolipid metabolism, as well as a small increase in other neurospherin-like lipids. In the cells of patients with types C and D, the main deposits are cholesterol and less sphingolipids, and sphingomyelinase is also reduced in the cells, with levels between those of types A and B and normal subjects. A significant impairment in the esterification of exogenous cholesterol (esteriification) was found in the skin fibroblasts of the patients, and based on this possible pathogenesis, pure-sibling, carrier and prenatal diagnostic methods have been established, which is therefore considered to be the cause of this type. The gene for sphingomyelinase is located on chromosome 17 and its structure is well understood. the mutation for type C is on chromosome 18.