Molybdenum cofactor deficiency

Molybdenum cofactor deficiency is a rare condition characterized by brain dysfunction (encephalopathy) that worsens over time. Babies with this condition appear normal at birth, but within a week they have difficulty feeding and develop seizures that do not improve with treatment (intractable seizures). Brain abnormalities, including deterioration (atrophy) of brain tissue, lead to severe developmental delay; affected individuals usually do not learn to sit unassisted or to speak. A small percentage of affected individuals have an exaggerated startle reaction (hyperekplexia) to unexpected stimuli such as loud noises. Other features of molybdenum cofactor deficiency can include a small head size (microcephaly) and facial features that are described as "coarse."

Tests reveal that affected individuals have high levels of chemicals called sulfite, S-sulfocysteine, xanthine, and hypoxanthine in the urine and low levels of a chemical called uric acid in the blood.

Because of the serious health problems caused by molybdenum cofactor deficiency, affected individuals usually do not survive past early childhood.