Mutation analysis in glutaric aciduria type I

Glutaric aciduria type 1 (GA1), resulting from the genetic deficiency of gl utaryl-CoA dehydrogenase (GDH), is a relatively common cause of acute metab olic brain damage in infants. Encephalopathic crises may be prevented by ca rnitine supplementation and diet, but diagnosis can be difficult as some pa tients do not show the typical excretion of large amounts of glutaric and 3 -hydroxyglutaric acids in the urine. We present a rapid and efficient denat uring gradient gel electrophoresis (DGGE) method for the identification of mutations in the glutaryl-CoA dehydrogenase (GCDH) gene that may be used fo r the molecular diagnosis of GA1 in a routine setting. Using this technique , we identified mutations on both alleles in 48 patients with confirmed GDH deficiency, while no mutations were detected in other patients with clinic al suspicion of GA1 but normal enzyme studies. There was a total of 38 diff erent mutations; 27 mutations were found in single patients only, and 21 mu tations have not been previously reported. Fourteen mutations involved hype rmutable CpG sites. The commonest GA1 mutation in Europeans is R402W which accounts for almost 40% of alleles in patients of German origin. GCDH gene haplotypes were determined through the analysis of polymorphic markers in a ll families, and three CpG mutations were associated with different haploty pes, possibly reflecting independent recurrence. The high sensitivity of th e DGGE method allows the rapid and cost efficient diagnosis of GA1 in insta nces where enzyme analyses are not available or feasible, despite the marke d heterogeneity of the disease.