Reflex testing for with aCGH yielded the corresponding second familial mutation; an approximately 58-kb deletion encompassing exon 9 of the BCKDHB gene (Figure 1a top) and an approximately 3.7-kb deletion encompassing exon 5 of the DBT gene were detected in the two above mentioned MSUD cases (Figure 1a bottom). Here, BCKDHB is linked to maple syrup urine disease.