Glutaryl-CoA dehydrogenase deficiency and newborn screening: retrospective analysis of a low excretor provides further evidence that some cases may be missed.

Glutaryl-CoA dehydrogenase deficiency (GA-I) is associated with the onset of irreversible, disabling dystonia between 3 and 18 months of age. Presymptomatic identification and treatment can prevent the devastating disability associated with this disorder. We report the retrospective analysis of the newborn blood spot of an affected child with a low excretor phenotype. The level of glutarylcarnitine was below the newborn screening program cut-off. This suggests that some cases of GA-I may be missed by newborn screening by tandem mass spectrometry.