1B BCKDHA, (p.Y438N), BCKDHB (p.R183P, p.E372X, p.G278S) is characterized in an infant by the presence of sweet-smelling urine, with an odor similar to that of maple syrup. Infants seem healthy at birth but if left untreated suffer severe brain damage, and eventually die. Treatment consists of a strict, lifelong special diet.