Poodle MHC DLA Class II Haplotypes
The latest results (April 2012) from Dr. Kennedy are a
sample of nearly 300 Standard Poodles from
In dogs, the Major Histocompatibility Complex (MHC) is called the Dog Leukocyte Antigen (DLA) and the portions of interest are the Class II genes which consist of three genes (named DRB1, DQA1 and DQB1). Every dog has two sets of these DLA genes, one from the sire and one from the dam. These genes may contain a number of different alleles. In dogs there have been found 172 different DRB1 alleles, 34 DQA1 alleles and 99 DQB1 alleles (as of 2012). This may seem like a lot, but the three genes are inherited as a group from each parent so there are limited pairings of these alleles. We call these pairings haplotypes. The number of haplotypes in each breed is limited, sometimes very limited. Of the 30 haplotypes found in Poodles, 19 have been seen in the Standard Poodle – up from the 3 known in 2007 – after a concentrated effort to search for more haplotypes. More may be found in Miniatures and Toys, but a special effort to do so has not begun.
The distribution of haplotypes across the sample (nearly 300) is shown in the graph below. As seen, Haplotype #1 is far more common than all the others. 88% of all Standard Poodles tested carried at least one copy of Haplotype #1, while 46% carried two copies.
Another way of looking at the distribution of Standard Poodle Haplotypes would be the pie chart below:
The distribution of coat colors across the sample is shown below. Dr Kennedy emphasized that the DLA is not linked to coat color in any way. In some cases a haplotype may have an association with a coat color, for example, preliminary analysis shows Haplotype #4 is coming from the old English apricot lines. The green bars (axis on the right) are the distribution of colors across 96,851 Standard Poodles born since 1/1/1995 which covers about the same time period as the DLA samples. The blues, silvers, and creams are somewhat over represented and the browns and reds somewhat underrepresented in the sample.
Or looking at color distribution by percentages:
Haplotypes by color are shown in the two charts below. Haplotypes #1 and #6 appear to be evenly distributed by color. Haplotype #4 is heavily apricot, as is Haplotype #14. In Haplotype #22 white is overly represented. Haplotype #26 is entirely blue and silver. Haplotype #11 and #22 are under represented in black.
Zooming in to see the minor haplotypes more clearly:
Each dog inherits one DLA Class II Haplotype from the sire and one from the dam. The 39 combinations seen in the sample are shown in the graph below: