October 19, 2015

Identification of a premature stop codon in MC1R in Labrador and Golden Retrievers with yellow coat colour

These researchers are looking at which specific gene in the genome controls the yellow coat color of labrador retrievers. Specifically, what difference in genetics is there between yellow labs and black labs? They hypothesize that the difference is at a genetic level in the MC1R gene. In order to investigate the gene the researchers first established that dogs have varying levels and placement of two kinds of pigments in order to create all of their coat colors. Then they started investigating just Labrador Retrievers’ genetic sequence. To begin the genetic analysis they isolated the DNA through the salt method established by Miller (1998). They tested 14 labs and compared those results to 48 dogs from 17 other breeds. Once the DNA was obtained it was put through Polymerase Chain Reaction (PCR).  The primers used for the PCR were established from the MC1R gene of a fox. This sequence had already been mapped in the fox and the primers were picked because the genes showed similarity. After amplification of the MC1R gene, inverse PCR was performed to create fragments for running through an agarose gel. After that they performed DNA sequencing, prepared slot blots, and performed an allele specific oligo analysis. From this they obtained the genetic sequence of Labrador Retrievers’ MC1R gene.

Analysis showed that the dogs had a similar sequence to the fox. The only difference between Black and Yellow labs is a single point mutation at position 916 from a C to a T causing a premature stop codon in yellow labs at position 305. They looked at how this trait was inherited by focusing on a litter of puppies born to two black parents; this litter was a mix of black and yellow. Through allele specific oligo nucleotide assay they found that this gene is inherited in a Mendelian pattern. Of the other breeds tested for the mutation, it was only found in Golden Retrievers who were homozygous for it.

Everts, R., Rothuizen, J., van Oost, B., 2002 Identification of premature stop codon in melanocyte-stimulating hormone receptor gene (MC1R) in Labrador and Golden Retrievers with yellow coat colour. Animal Genetics 31: 194-199.​

Retrieved from:

 

http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2052.2000.00639.x/full