Original
MSUD also known as Branched chain ketoaciduria was discovered in 1954 by Dr. John Menkes as the inability to metabolize the branched chain amino acids (BCAA's) which would then build up and cause toxicity.
https://www.msud-support.org/index.php/newsletter/13-volume-11-2/41-a-brief-history-of-maple-syrup-urine-disease-msud