"Molybdenum is an essential trace element, forming part of a molybdenum cofactor, which is vital for the normal functioning of several enzymes, including sulfite oxidase and xanthine dehydrogenase. In molybdenum cofactor deficiency, the activity of these enzymes is reduced. The genes MOCS1, MOCS2, MOCS3, and GEPH encode critical components for the synthesis of molybdenum cofactor, and it is mutation of these genes that leads to the condition, most commonly MOCS1."