Identification of brachyspina syndrome carriers in Chinese Holstein cattle

Brachyspina syndrome (BS) is a rare monogenic autosomal recessive hereditary disorder identified in the Holstein breed caused by a 3.3-kb deletion in the bovine Fanconi anemia complementation group I (FANCI) gene on chromosome 21. In previous reports, the BS mutant allele was identified in North American and European Holstein populations. Because frozen semen and embryos have been imported into China from such regions during the past few years, BS has potentially spread into the dairy cattle population in China. In the present study, 206 Holstein bulls and 136 Holstein cows were tested for BS, with 10 BS carrier bulls and 3 carrier cows identified. Pedigree analysis showed that all 10 BS carrier bulls could be traced back to a common ancestor, the U.S. Holstein sire Sweet Haven Tradition. It is recommended that effective selection and mating strategies should be carried out to gradually eliminate this recessive gene from the Chinese Holstein population.