How long before the Y is incorporated into association studies?


I’ve been reading Sperm Biology: An Evolutionary Perspective; an engaging comparative look at, well, sperm biology. One fairly remarkable thing to me is that, while sperm evolve incredibly rapidly in morphology (at one point in the book, the claim is made that just about any animal can be distinguished visually by sperm cells alone[1]), the precise genetic changes involved in this variation are entirely unknown.

Given that the human and chimp Y chromosomes have diverged massively, the rapid evolution of sperm, and the fact that many genes on the Y are involved in spermatogenesis, it stands to reason that there is a large amount of variation within current human populations (there is very little work on this, so direct evidence of this is hard to come by), and that some of the relevant genetic loci lie on the Y chromosome.

So how variable is the Y chromosome within humans? It appears this is largely unknown as well (outside of the markers used for ancestry testing and the like), largely due to the fact that its repetitiveness makes it difficult to genotype or sequence. Here’s the thought: Pacific Biosciences now claims to be able to generate quality sequencing reads of up to a few kilobases; this alone might be enough to overcome the repetitiveness of the Y. Is it time for a “HapMap” of the Y chromosome, and incorporation of this chromosome into association studies for relevant traits?

[1] random aside: many nemotodes, including C. elegans, have ameoba-like sperm, rather than flaggela. How many C. elegans genetics talks have I listened to without knowing this? Many.


  1. fun fact: C. elegans male and hermaphrodite sperm are different sizes; male sperm are bigger

  2. Biologist (in re: worm porn)

    I recall reading (title, author, lost to memory–or lack of), back in the mid-60s, a sci-fi short story in which one character, a wanted criminal pornographer on his own planet, comes to Earth and does well by contributing his photos for a Biology text (his life form resembled something here but I forget that, also).

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