Outcome of medium chain acyl-CoA dehydrogenase deficiency after diagnosis

Background-Medium chain acyl-CoA dehydrogenase (MCAD) deficiency is the most common inborn error of fatty acid metabolism. Undiagnosed, it has a mortality rate of 20-25%. Neonatal screening for the disorder is now possible but it is not known whether this would alter the prognosis. Objective-To investigate the outcome of MCAD deficiency after the diagnosis has been established. Method-All patients with a proved diagnosis of MCAD deficiency attending one centre in a four year period were reviewed. Results-Forty one patients were identified. Follow up was for a median of 6.7 years (range, 9 months to 14 years). Nearly half of the patients were admitted to hospital with symptoms characteristic of MCAD deficiency before the correct diagnosis was made. After diagnosis, two patients were admitted to hospital with severe encephalopathy but there were no additional deaths or appreciable morbidity. There was a high incidence (about one fifth) of previous sibling deaths among the cohort. Conclusions-Undiagnosed, MCAD deficiency results in considerable mortality and morbidity. However, current management improves outcome, supporting the view that the disorder should be included in newborn screening programmes.