NPP6 is a 440 amino acid member of the nucleotide pyrophosphatase/phosphodiesterase family. NPP6 is a secreted and single-pass type I membrane protein. Predominantly expressed in brain and kidney, NPP6 is a choline-specific glycerophosphodiester phosphodiesterase. NPP6 can hydrolyze the classical substrate for phospholipase C, p-nitrophenyl phosphorylcholine, glycerophosphorylcholine, sphingosylphosphorylcholine and lysophosphatidylcholine (LPC). NPP6 has been found to have a preference for LPC with polyunsaturated or short fatty acids. The gene encoding NPP6 maps to human chromosome 4, which consists of approximately 6% of the human genome and nearly 900 genes. Chromosome 4 is associated with Huntington's disease, FGFR-3, Ellis-van Creveld syndrome, methylmalonic acidemia and polycystic kidney disease.