IDENTITY-BY-DESCENT MAPPING OF RECESSIVE TRAITS IN LIVESTOCK - APPLICATION TO MAP THE BOVINE SYNDACTYLY LOCUS TO CHROMOSOME-15

Twelve animals affected with syndactyly or mulefoot were sampled in th e Dutch black-and-white cattle population. Analysis of the pedigree da ta revealed that all of these individuals traced back to a single ackn owledged carrier founder individual. Between seven and nine generation s separated the Founder from its 12 affected descendants. The 12 affec ted offspring were genotyped For a battery of 213 microsatellites span ning the 29 bovine autosomes. The resulting genotypes were analyzed us ing a maximum likelihood approach searching for shared homozygous hapl otypes among affected individuals. Three candidate regions For the syn dactyly locus emerged from this initial screening, syndactyly was show n to map to one of these candidate regions on chromosome 15 by genotyp ing 29 additional individuals linking founder and affected offspring a nd performing a conventional linkage analysis with the LINKAGE program s. This study illustrates the potential of identity-by-descent mapping in livestock populations.