Mutation of human molybdenum cofactor sulfurase gene is responsible for classical xanthinuria type II

Drosophila ma-l gene was suggested to encode an enzyme for sulfuration of the desulfo molybdenum cofactor for xanthine dehydrogenase (XDH) and aldehyde oxidase (AO). The human molybdenum cofactor sulferase (HMCS) gene, the human nra I homologue, is therefore a candidate gene responsible for classical xanthinuria tape II, which involves both XDH and AO deficiencies. However, HMCS has not been identified as get. In this study, we cloned the HMCS gene from a cDNA library prepared from liver. In two independent patients with classical xanthinuria type II, we identified a C to rf base substitution at. nucleotide 1255 in the HMCS gene that should cause a CGA. (Arg) to TG,I (Ter) nonsense substitution at codon 419. A classical xanthinuria type I patient and healthy volunteers lacked this mutation. These results indicate that. a functional defect of the HMCS gene is responsible for classical xanthinuria type II, and that HMCS protein functions to provide a sulfur atom for the molybdenum cofactor of XDH and XQ. (C) 2001 Academic Press.