Since the addition of the acylcarnitine profile to the newborn screen, debates about which conditions to include an exclude are becoming a very important issue. There are several “conditions” that are detected that are thought to be probably clin
ically insignificant. One of these “conditions” is 2-Methylbutyryl-coenzyme A dehydrogenase deficiency, in which an elevation of pentanoylcarnitine is detected and 2-MBG can be detected on urine organic acids. Some groups have also demonstrated an in vitro deficiency of this enzyme in affected individuals. However, there remains to be conclusive evidence that this enzyme deficiency leads to specific or significant clinical consequences. I am hoping that as we gain further experience with these types of newborn screening results, there will be conclusive and authoritative studies on large numbers of individuals that will settle these questions!
Hilary Vernon, MD PhD