has material basis in germline mutation in BCKDHB maple syrup urine disease maple syrup urine disease type 1B https://rarediseases.info.nih.gov/diseases/8597/maple-syrup-urine-disease-type-1b https://www.malacards.org/card/maple_syrup_urine_disease_type_ib MSUD type 3 (formerly) MONDO:0023692 MSUD type IB A maple syrup urine disease caused by mutations in BCKDHB. MEDGEN:443951 MSUD due to deficiency of E1-beta subunit of branched-chain alpha-keto acid dehydrogenase complex DOID:0061206 GARD:0008597 maple syrup urine disease type 1B UMLS:C2930990 OMIM:620698