sy, smoky or slate

[jeffmannza]

The smoky or 'slate' phenotype (see pic, a slate blue bar hen — she has flown a 800 km race) is caused by inactivation of the 'melanocortin 1 receptor 1' (Mc1r) gene, synonym 'sy'. The mutation is a large deletion of the protein coding region, and would almost certainly result in complete loss of MC1R protein function, i.e. the mutation can be safely be classified as a 'null'. The mutation is recessive, so the pigeon has to be homozygous (two copies) to be a slate. In humans, mutations in the equivalent gene are responsible for red hair colour. The effect in pigeons of course is not the same, although some reddish hue can be seen, e.g. adjacent the barred region.
REF: https://www.biorxiv.org/content/10.1101 ... 1.full.pdf