Fosdenopterin

Molybdenum cofactor deficiency (MoCD) is a rare autosomal-recessive disorder in which patients are deficient in three molybdenum-dependent enzymes: sulfite oxidase (SOX), xanthine dehydrogenase, and aldehyde dehydrogenase. The loss of SOX activity appears to be the main driver of MoCD morbidity and mortality, as the build-up of neurotoxic sulfites typically processed by SOX results in rapid and progressive neurological damage. In MoCD type A, the disorder results from a mutation in the MOCS1 gene leading to deficient production of MOCS1A/B, a protein that is responsible for the first step in the synthesis of molybdenum cofactor: the conversion of guanosine triphosphate into cyclic pyranopterin monophosphate (cPMP).

Fosdenopterin is an exogenous form of cPMP, replacing endogenous production and allowing for the synthesis of molybdenum cofactor to proceed.