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:
