They produce a deficiency in the activity of the lysosomal enzyme acid sphingomyelinase, that breaks down the lipid sphingomyelin.Mutations in NPC1 or NPC2 cause Niemann–Pick disease, type C (NPC), which affects a protein used to transport lipids.Type D originally was separated from type C to delineate a group of patients with otherwise identical disorders who shared a common Nova Scotian ancestry. Patients in this group are known to share a specific mutation in the NPC1 gene, so NPC is used for both groups. Before the molecular defects were described, the terms "Niemann–Pick type I" and "Niemann–Pick type II" were proposed to separate the high- and low-sphingomyelin forms of the disease in the early 1980s.Niemann–Pick disease is inherited in an autosomal recessive pattern, which means both copies, or both alleles of the gene, must be defective to cause the disease. "Defective" means they are altered in a way that impairs their function. Most often, the parents of a child with an autosomal recessive disorder are carriers: they have one copy of the altered gene, but are not affected because the other copy produces the enzyme. If both parents are carriers, each pregnancy has a 25% chance of producing an affected child. Genetic counseling and genetic testing are recommended for families who may be carriers of the disease.
In medicine, pleocytosis (or pleiocytosis) is an increased cell count (from Greek pleion, "more"), particularly an increase in white blood cell count, in a bodily fluid, such as cerebrospinal fluid. It is often defined specifically as an increased white blood cell count in cerebrospinal fluid.Increased white blood cell count in the blood is called leukocytosis. == References ==