In Poll Herefords, it is known that maple syrup urine disease results
from a nonsense mutation in codon -6 of the gene for the E1 alpha subu
nit of branched-chain alpha-keto acid dehydrogenase. The disease also
occurs in Poll Shorthorns, but its molecular basis in this breed has n
ot yet been determined. Allele-specific hybridization and allele-speci
fic amplification, both based on the Poll Hereford mutation, failed to
detect the mutant allele in Poll Shorthorn heterozygotes, and detecte
d the normal allele in affected Poll Hereford-cross-Poll Shorthorn cal
ves. These results demonstrate between breed molecular heterogeneity f
or bovine maple syrup urine disease.