You've probably heard about your segments that you share with other people. And you might be wondering. Well, do I have segments everywhere? In fact, do I have segments on all of my chromosomes?
During a recent conference, I got the question about the Y chromosome and whether there are segments on the Y chromosome.
As with most things that involve DNA, the answer is no and yes.
Males Pass on Y Chromosomes to Their Sons
For those who are just getting into genetic genealogy, remember the Y chromosome is passed on from father to son. It's never passed on to daughters. Since males only have one Y chromosome, there's not another chromosome for it to recombine with.
Segments are made through recombination. And so, you would not expect any segments on the Y chromosome. And that's why I say no.
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What are pseudoautosomal regions?
Both the X and the Y chromosomes have tiny regions on either end called pseudoautosomal regions. These regions actually have the capability of recombining.
In other words, in men, when sex cells pass on their genes, the Y and the X chromosomes line up together. And sometimes, those pseudoautosomal regions will swap places. They'll recombine.
Will a Chromosome Browser Show the Pseudoautosomal Region?
You might be wondering if you can see the recombinations of the sex cell endpoints. The answer is no because these are such small segments.
To give you an idea, one pseudoautosomal region is only 2.6 million bases long. While that may sound like a lot, a centimorgan is about one million bases on average.
Since the Y chromosome is only about 2.6 centimorgans in length, it won't show up in any commercial genetical genealogy analysis. Almost every DNA test result will only show segments at least 7 centimorgans long. Other regions are even smaller.
Therefore, your y-DNA will never have segments to research to find your common ancestors because they are too short to be seen on any chromosome browser.
Researching y-DNA will focus on SNPs and is only available through Family Tree DNA.
I actually have more to say about y-DNA segments, so check out this video below.
To learn more about y-DNA testing, check out my videos:
You might also like my video on An Introduction to the FamilyTree DNA website.
For other tips on genetic genealogy, check out this list: