Medium-chain acyl-CoA dehydrogenase deficiency

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is an autosomal recessive disorder of fatty acid oxidation with an incidence in the UK of more than 1:10,000. The majority of patients are homozygous for a missense mutation c.985A > G. Newborn screening for this condition was implemented in England and Northern Ireland in 2009 in Scotland in 2010 and in Wales in 2012. Patients with MCADD are at risk during periods of fasting stress, particularly during intercurrent infections, of developing an encephalopathy associated with hypoketotic hypoglycaemia. These episodes can be prevented by giving high calorie drinks (the emergency regimen) during periods of illness but hospital admission is required for intravenous dextrose if the emergency regimen is not tolerated. No specific treatment is required at other times. This review highlights the pathogenesis, the presentation and management of MCADD.