The clinical significance of 3-MCC deficiency is a hotly debated topic, which rears it’s head in our own metabolism department every time a newborn screen is positive for this disorder. It is often difficult to describe the possible clinical consequencesÂ of this to new parents, and to provide guidelines for the short and long term follow up of these patients. Grunert et al, (Orphanet J Rare Dis. 2012 May 29;7(1):31) describes a well characterized cohort of 88 individuals with 3-MCC deficiency including biochemical profile, genotype, and clinical outcome. Suprisingly to me, 12 of the 88 patients had acute metabolic decompensation. This amounts to approximately 14% of affected patients, which, while significantly less than patients with other “classic” organic acidemias, is not a negligible number. This article provides evidence that this is a disorder to be taken seriously,Â even thoughÂ the overwhelming majority of patients do well.
Hilary Vernon MD PhD