In this article, you will learn what a haplotype is, how they are determined, and why some dogs don’t have paternal haplotypes.
Canine genomicists have put an incredible amount of work into describing haplotypes (patterns of DNA sequences) in the domestic dog and its related species. Haplotypes and their relatedness across the canid species have been published in peer-reviewed articles and publicly available datasets. Embark has built upon these with our own data to produce one of the most comprehensive haplotype databases in the world.
But first, what is a haplotype?
A haplotype is a group of genes within an organism that was inherited from a single parent. "Haplotype" is a generic term for a single copy of a dog’s diploid genotype (haploid = 1 copy, diploid = 2 copies). Dogs will have 2 copies of their autosomes (non-sex chromosome), so parent A's copy and parent B's copy are each inherited as a single unit, each referred to as a haplotype.
How are they determined?
Due to how dog breeds have been generated, each breed has its own set of unique haplotypes. We use these breed-specific haplotypes to determine the percentage of breeds present in your dog.
Mitochondrial DNA (mtDNA) and Y chromosome haplotypes can also be used to trace maternal and paternal lineage. Mitochondrial DNA is inherited solely from the mother and passed on to sons and daughters, whereas the Y chromosome is inherited solely from the father and is passed on to only sons.
You may have noticed that we also categorize your dog's mtDNA and Y haplotypes by haplogroups, simply groups of related haplotypes. Just like a genus is a group of species that originated from a common ancestor, we can determine if haplotypes have originated from an ancestral sequence.
Why isn't there a Paternal Haplotype for my dog?
Because she's female! :)
In order to report on the father’s geographical ancestry, we would have to look at the Y chromosome haplotype but, because your dog is female, she doesn’t have a Y chromosome to look at.
Every dog has two sex chromosomes (well, there are very rare exceptions, but for the most part dogs are going to have two sex chromosomes). Female dogs have two X-chromosomes (XX) and male dogs have one X-chromosome and one Y-chromosome (XY). When having offspring, female (XX) dogs pass one of their two X-chromosome copies to their puppy. Male (XY) dogs can pass either an X (resulting in a daughter) or a Y-chromosome (son). As you can see, Y-chromosomes are passed down from a sire to all of his male offspring, and daughters do not receive any genetic material from their father's Y. In other words, we, cannot determine any information about the paternal haplotype in female dogs because that entire chromosome is completely missing from their genome. However, that does not mean that only half a dog's DNA is tested merely because they are female
While we cannot trace the Paternal Haplotype of female dogs, we are still fully able to identify the ancestry contributed by both the male and female parent, which you can view in the Breed section of your results.
Have questions? Your MyEmbark account includes information about your dog's sample status, your dog's results, and many other helpful resources. Log in to your account here!