DLD and maple syrup urine disease: Five clinical phenotypes of MSUD based on severity, age of onset, residual BCKD enzyme activity and thiamine responsiveness: classical, intermittent, intermediate, thiamine responsive and the E3 deficient that is associated with combined enzyme deficiencies in pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and BCKD, because E3 is a common component among these mitochondrial enzymes8,9.