Exfoliative erythroderma resulting from inadequate intake of branched-chain amino acids in infants with maple syrup urine disease

To the Editor.—

Maple syrup urine disease (MSUD) is caused by a block in the breakdown of three branched-chain amino acids (BCAAs): leucine, isoleucine, and valine.¹We describe an infant with classic MSUD where inadequate dietary intake of BCAAs²resulted in an exfoliative dermatitis. When the BCAA intake was increased, the eruption resolved.

Report of a Case.—

A 4.5-month-old boy presented at another hospital with hypoglycemia, acidosis, and seizures requiring intubation and phenobarbital therapy. Physical examination was unremarkable except for mild hepatomegaly and marked growth retardation. By day 3 of hospitalization, he was extubated. His unusual urine odor led to an evaluation for MSUD, and the infant received a BCAA-deficient diet. Seven days before he was transferred to our hospital, gradually worsening skin changes developed. Amino acid levels drawn prior to his transfer revealed the following elevated values: valine, 595.5 μmol/L (normal, 145 to 316 μmol/ L); leucine,