Molybdopterin synthase mutations in a mild case of molybdenum cofactor deficiency

Molybdenum cofactor deficiency is a rare inborn error of metabolism with ge nerally severe symptoms, most often including neonatal seizures and severe developmental delay. We describe a patient with an unusually mild form of t he disease. Two mutations in MOCS2A (molybdenum cofactor synthesis enzyme 2 A) were identified: a single base change, 16C > T, that predicts a Q6X subs titution on one allele and a 19G > T transversion that predicts a valine to phenylalanine substitution, V7F, on the second. It is postulated that the milder clinical symptoms result from a low level of residual molybdopterin synthase activity derived from the 19G > T allele. (C) 2001 Wiley-Liss, Inc .