Phenotypes

In a remarkable indication of the power of whole-genome sequence analysis, Daetwyler et al. (2014) identified a causal mutation for this disorder in Holstein Friesian cattle as a missense mutation (g.32475732G>A [UMD3.1 reference sequence]; p.Gly960Arg, omia.variant:223) in the COL2A1 gene (which encodes the alpha-1 chain of type II collagen), by comparing the sequence of only two affected calves with sequence from bulls in the 1000-bull-ge...

In the words of Charlier et al. (2008), "All calves with CMD have episodes of generalized muscle contractures, but careful clinical examination suggested two distinct phenotypes (CMD1 and CMD2)." 

For eight of the nine haplotypes with a significant effect on calving rate (see Mapping section), Fritz et al. (2013) searched for causal mutations via whole-genome sequence data from 25 Holstein, 11 Montbéliarde and nine Normande bulls which had made major contributions to their breed. Specifically, they filtered "for mutations that were (a) located at+or –6 Mb from the detected haplotype (b) carried in the heterozygous state by the carrier b...

Exome sequencing by Sasaki et al. (2016) within the candidate region (see Mapping section) revealed a likely causal missense variant: g.62382825G > A, p.Pro372Leu) in exon 10 of solute carrier family 12, member 1 (SLC12A1).

Recognising the close resemblance of this disorder in Chianina cattle to Brody disease in humans, Drögemüller et al. (2008) illustrated the power of the candidate-gene approach by showing that this disorder in Chianina cattle is due to a missense mutation in the bovine version of the "Brody gene" - ATP2A1. Interestingly, another mutation in this same gene causes a far more severe set of clinical signs: congenital muscular dystonia 1 (OMIA 0014...