urothion and Metabolism--Inborn-Errors

Topics: Biomarkers; Coenzymes; Humans; Metabolism, Inborn Errors; Metalloproteins; Molybdenum; Molybdenum Cofactors; Pteridines; Pterins

Molybdenum cofactor deficiency was diagnosed in a 3-month-old girl who presented with microcephaly, developmental delay, severe irritability, and lactic acidosis. Dietary methionine restriction, with cysteine supplementation, was associated with moderate short-term clinical improvement, including a resumption in predicted head growth, modest developmental progress, and a reduction in irritability. Clinical relapse was associated with noncompliance of dietary therapy 2 months later. Urinary sulfite levels measured by commercial dipsticks were useful in following therapy. Molybdenum cofactor deficiency is probably frequently underdiagnosed due to the lack of specific clinical or laboratory features. Screening of infants at risk for the presence of urinary sulfites or serum hypouricemia, or both, is both rapid and inexpensive.

Topics: Acidosis, Lactic; Coenzymes; Cysteine; Developmental Disabilities; Female; Food, Fortified; Humans; Infant; Lactates; Metabolism, Inborn Errors; Metalloproteins; Methionine; Microcephaly; Molybdenum Cofactors; Pteridines

Increased urinary excretion of xanthine, hypoxanthine, sulphite, thiosulphate and decreased serum uric acid were observed in an infant with profound failure to thrive. Other clinical findings included refractory seizures, spastic quadriplegia and profound psychomotor retardation. The patient died at 20 months of age. There were no detectable activities for xanthine oxidase and sulphite oxidase in the postmortem liver. Urothione, which is the metabolic excretory product of the molybdenum cofactor for molybdoenzymes was not present in the urine. A deficiency of the molybdenum cofactor which is common to both xanthine and sulphite oxidase is presumed to be the metabolic defect responsible for the absent activities of both enzymes.

Topics: Coenzymes; Humans; Infant, Newborn; Liver; Male; Metabolism, Inborn Errors; Metalloproteins; Molybdenum Cofactors; Oxidoreductases; Oxidoreductases Acting on Sulfur Group Donors; Pteridines; Sulfites; Xanthine; Xanthine Oxidase; Xanthines