Carnosine Dipeptidase 1 (CNDP1) belongs to the M20 metalloprotease family. CNDP1 is specifically expressed in the brain, serum and adult nervous central system. It is identified as human carnosinase. CNDP1 contains trinucleotide (CTG) repeat length polymorphism in the coding region and is inhibited by the metal chelator 1,10-o-phenantrolin. In addition, CNDP1 can hydrolyse the beta-Ala|-His dipeptide (carnosine), anserine, Xaa-|-His dipeptides and other dipeptides including homocarnosine. CNDP1 deficiency has been associated with homocarnosinosis disease.