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)

By cloning and sequencing a very likely comparative candidate gene (based on the homologous human disorder), Dennis et al. (2000) identified two causal mutations in Brahman cattle, namely a frameshifting 2-bp deletion (c.1057delTA; the "E7" mutation) and a nonsense mutation (c.1783C>T; p.Arg595Ter; the "E13" mutation) in the bovine GAA gene; and a 2-bp frameshifting deletion (c.2454delCA; the "E18" mutation) in Shorthorns.

See also: 'OMIA:001009-9915 : Hemimelia, tibial in Bos indicus'

In the words of Charlier et al. (2008): "a missense mutation in exon 39 (A5804G) resulting in an H1935R substitution in the fourth extracellular loop". The His (normal) form of the peptide is conserved in all vertebrates sequenced to date. (FN 080330) Whole-genome sequencing of the affected Shorthorn calf described by O'Rourke et al. (2017), and subsequent checking for deleterious variants in functional candidate genes, enabled Woolley et al. ...

Maple Syrup Urine Disease (MSUD) is an autosomal recessive defect reported in Poll Hereford (PH) and Poll Shorthorn (PS) calves (Harper et al., 1986; Healy et al., 1992). The clinical, biochemical and pathological characters of the disease are identical in the two breeds of cattle, and are characterised by the rapid onset of progressive neurological disease, resulting in death within a few days of birth. The disease is caused by a deficiency o...