Phenotypes

By cloning and sequencing a very likely comparative positional candidate gene (see the Genetic mapping section above), Seitz et al. (1999) reported that a missense mutation at 654 bp (amino acid 193, Ala>Asp) in the mast cell growth factor (MGF) locus is responsible for the roan phenotype in Belgian Blue and Shorthorn cattle (Mohammad Shariflou. The MGF gene is now called KITLG (10/11/2006; FN 15/9/2012)

This disorder is of particular interest in cattle, because it is one of the few cases in which an embryonic lethal has been identified. (By their very nature, embryonic lethals are difficult to identify; their only manifestation is a return to service.) To date, the only known cause of this disorder in cattle is a nonsense mutation in codon 405 of the UMPS gene, resulting in a complete deficiency of functional UMPS (Schwenger et al., 1993). Si...

In a conference abstract, Haton et al. (2000) reported that, by cloning and sequencing a very likely comparative candidate gene (based on the homologous human disorder), they had identified a 76-bp insertion in exon 12 of the Factor XI gene as being causative of Factor XI deficiency in Holstein cattle. This discovery was fully described by Marron et al. (2004) who explained that "This insertion introduces a stop codon that results in a mature ...

Null et al. (2017): "A splice acceptor variant at 51,267,548 bp in the RNA Polymerase 2 Associated Protein (RPAP2) gene was the most likely causal variant in the [AH2] haplotype. RPAP2 is an essential component of the RNA polymerase 2 holoenzyme necessary for transcription of snRNA species. Experiments with mouse knockouts also found a deficiency of homozygotes, suggesting that RPAP2 is necessary for embryonic development."

Häfliger et al. (2021) investigated “the two Braunvieh populations reared in Switzerland, the dairy Brown Swiss (BS) and the dual-purpose Original Braunvieh (OB). We performed a genome-wide analysis of array data of trios (sire, dam, and offspring) from the routine genomic selection to identify candidate regions showing missing homozygosity and phenotypic associations with five fertility, ten birth, and nine growth-related traits. In addition,...

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...

Within the mapped candidate region (see Mapping section), Fritz et al. (2018) identified a likely causal variant as "an A-to-G transition at position 29,773,628 bp on chromosome 16 (g.29773628A>G; rs434666183)". The authors explained that "This A-to-G transition changes the initiator ATG (methionine) codon to ACG because the gene is transcribed on the reverse strand. . . . Initiation of translation at the closest in-frame Met codon would tr...

Häfliger et al. (2021) investigated “the two Braunvieh populations reared in Switzerland, the dairy Brown Swiss (BS) and the dual-purpose Original Braunvieh (OB). We performed a genome-wide analysis of array data of trios (sire, dam, and offspring) from the routine genomic selection to identify candidate regions showing missing homozygosity and phenotypic associations with five fertility, ten birth, and nine growth-related traits. In addition,...

"Affected animals have a crooked tail and shortened head, growth retardation, extreme muscularity and spastic paresia, although some characteristics show variable penetrance. CTS is not lethal per se, but causes substantial economic losses due to growth retardation and treatment." (Charlier et al., 2008)