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)

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)." 

Khalaj et al. (2009): "A nucleotide substitution of T to A resulting in an amino acid substitution of leucine to histidine (p.Leu2153His) was identified in a highly conserved residue in the C1 domain of factor VIII. Genotyping of 254 normal animals including the pedigree of the affected animals and randomly sampled animals of different breeds confirmed that the substitution is the causative mutation of cattle haemophilia A." Analysis of whole-...

Besnard et al. (2023) "present a data-mining framework designed to detect recessive defects in livestock that have been previously missed due to a lack of specific signs, incomplete penetrance, or incomplete linkage disequilibrium. This approach leverages the massive data generated by genomic selection. Its basic principle is to compare the observed and expected numbers of homozygotes for sliding haplotypes in animals with different life histo...

Besnard et al. (2023) "present a data-mining framework designed to detect recessive defects in livestock that have been previously missed due to a lack of specific signs, incomplete penetrance, or incomplete linkage disequilibrium. This approach leverages the massive data generated by genomic selection. Its basic principle is to compare the observed and expected numbers of homozygotes for sliding haplotypes in animals with different life histo...

Sieck et al. (2020): "Whole-genome sequencing (WGS) of 20 animals [including 3 affected calves] led to the discovery of a variant (Chr26 g. 14404993T>C) in Exon 3 of CYP26C1 associated with MD. This missense mutation (p.L188P), is located in an α helix of the protein, which the identified amino acid substitution is predicted to break"

Abbitt et al. (1991) reported that bovine beta-mannosidosis, a lysosomal storage disease, is caused by a deficiency of beta-mannosidase. Affected neonatal calves are unable to rise with intention tremors, hidebound skin, slightly domed calvaria, slight prognathism, and narrow palpebral fissures. Their postmortem findings included variable dilatation of the lateral cerebral ventricles, marked pallor and paucity of white matter of the cerebrum a...

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...

By examining three comparative positional candidate genes from their mapping results (see Mapping section), Krebs et al. (2007) reported strong evidence that this disorder in cattle is due to a mutation in "FVT1, encoding 3-ketodihydrosphingosine reductase, which catalyzes a crucial step in the glycosphingolipid metabolism". Specifically, the mutation is "a G-to-A missense mutation that changes Ala-175 to Thr". Interestingly, the FVT1 gene, of...

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 ...

Cloning and sequencing of the bovine gene encoding molybdopterin cofactor sulfurase (MCSU, now called MOCOS) in normal and affected cattle, by Watanabe et al. (2000), revealed the causal mutation to be a 3bp deletion (c.769_771delTAC) of codon 257 (deleting Tyr) in the MOCOS gene (omia.variant:446). Murgiano et al. (2016) discovered a different mutation in the MUCOS gene as the likely cause in Tyrolean Grey cattle: "1 bp deletion in the molybd...