The most important metabolic conditions to consider are pyridoxine/ pyridoxal-p-phosphate–dependent epilepsy, nonketotic hyperglycinemia, molybdenum cofactor deficiency and sulfite oxidase deficiency, mitochondrial disorders, and organic acidurias—urea cycle disorders [36–38]. The gene discussed is OCA2; the disease is sulfite oxidase deficiency due to molybdenum cofactor deficiency.