Phenotypes

By sequencing the most likely functional positional candidate gene from the mapped region (see Mapping section), Littlejohn et al. (2014) identified a causal mutation as a "nonsynonymous SNP in exon 5 [that] encodes a p.Cys221Gly substitution highly conserved across vertebrates and other structurally related hormones, disrupting one of three disulphide bonds defining the three-dimensional (3D) structure of mature prolactin hormone" (ss10672894...

Syndactyly has been reported in many breeds of cattle in many countries. Most of the documentation, however, concerns its occurrence in US Holsteins, where, as a result of the siring of more than 60,000 calves by a bull who was subsequently shown to be a carrier, the disorder attracted considerable attention (Anon., 1967). The possibility that artificial selection favouring heterozygotes may have contributed to the unacceptably high frequency ...