Ricki Lewis

Sequencing our genomes is a 21rst century phenomenon. Discrimination based on genetics dates back to the start of the eugenics movement in the 1880s. Will an effort to determine the sex chromosome constitutions of nearly 600,000 men whose DNA is being analyzed in the Million Veteran Program provide helpful health information – or highlight another possible source of genetic judgment?

 

Researchers at the University of Colorado Anschutz Medical Campus and collaborators across the US report the largest and most diverse study of men with extra X or Y chromosomes in the US. Their findings appear in the March 29, 2024 JAMA Network Open. The Million Veteran Program is a national effort considering how genes, lifestyle, military experiences, and environmental exposures affect health and wellness among veterans. It launched in 2011.

 

The Biology of Sex Chromosomes

I've never been fond of the human Y chromosome. Yes, the all-important SRY gene sets the early embryo on a path towards maleness, but the rest? Mostly DNA borrowed from a long-ago X, peppered with eight long palindromes.

 

"The Y is a pathetic little chromosome with lots of junk. It is gene-poor, prone to deletion, and useless. You can lack a Y and not be dead, just female," Jennifer Marshall Graves told me years ago when I defiled the Y in The Scientist. She's professor emeritus of Australian National University, an evolutionary geneticist who works on kangaroos, platypus, Tasmanian devils, and various dragon lizards.

 

But men missing the Y in some of their white blood cells face heightened health risks. That was a mere association a few years ago, but now appears to be causal, according to results of an investigation in Science from researchers at Uppsala University. The research combines clues from mouse studies and epidemiological data from the UK Biobank.

 

To continue reading go to DNA Science, where this post first appeared.

The firing of CBS CEO Les Moonves for his alleged history of revolting attacks on women and the upcoming one-year anniversary of Ronan Farrow’s seminal New Yorker piece on Harvey Weinstein and of Alyssa Milano’s #MeToo tweet echoing Tarana Burke’s 2006 call-to-action, got me pondering the Y chromosome.

Genomically speaking, the diminutive Y is the only thing that distinguishes males from females (see “Y Envy"). Both sexes have X chromosomes, and although mitochondrial DNA passes from females to all offspring, we all have mitochondria. Only the Y is the male’s alone.

If size matters, the Y chromosome loses. The human X has about 1500 protein-encoding genes compared to the Y’s 231, some of which have counterparts on the X. Only a handful of Y genes, in the “male-specific region” of the chromosome, are uniquely male. They include the SRY gene that determines maleness and a few others that control fertility.

So the Y chromosome can tell us some interesting things about the male of the species.

To continue reading go to DNA Science, where this post first appeared. Read More 

Let me get this straight: The human Y chromosome has barely changed from that of a rhesus macaque, a monkey from whom we parted ways some 25 million years ago, and that’s good news? I suppose compared to disappearing, it is.

For several editions now, my human genetics textbook has run an “In Their Own Words” essay in which MIT’s David Page, protector of the Y, has defended the measly male chromosome against charges from Jennifer A. Marshall-Graves, of Australian National University, that it is disappearing. She helpfully points out in my book, “You can lack a Y and not be dead, just female,” then goes on to call the Y “a pathetic little chromosome that has few genes interposed with lots of junk.”  Read More