ENPP4 (Ectonucleotide Pyrophosphatase/Phosphodiesterase 4): ENPP4 is a gene that encodes an enzyme from the ENPP family, involved in purinergic signaling and phosphate balance. ENPP4 functions as both a phosphodiesterase, breaking down phosphodiester bonds, and a pyrophosphatase, cleaving pyrophosphate bonds. It is primarily expressed in the kidney, liver, and brain, where it plays a role in processes such as bone mineralization, lipid metabolism, and regulation of extracellular nucleotides. ENPP4 may also affect immune responses and inflammation through interactions with purinergic receptors.