NT5M is a member of the 5’(3’)-deoxyribonucleotidase family. NT5M localizes to the mitochondrial matrix. The NT5M enzyme dephosphorylates the 5’- and 2’(3’)-phosphates of uracil and thymine deoxyribonucleotides. The NT5M gene is located on chromosome 17 p11.2 in the critical region deleted in the Smith-Magenis syndrome(SMS), a genetic disease of unidentified etiology.