Molybdenum cofactor deficiency, xanthinuria type III, a rare autosomal recessive neurodegenerative disorder is characterised by a combined deficiency of molybdenum cofactor-dependent enzymes sulfite oxidase, xanthine dehydrogenase and aldehyde oxidase [6, 7]. Here, SUOX is linked to sulfite oxidase deficiency due to molybdenum cofactor deficiency.