Why are men, on average, taller than women? A massive new genetic study reveals how a single gene may account for a slice of the difference. The SHOX gene has been thought to influence height—but since it's present on both X and Y chromosomes, researchers could only hypothesize that the gene acts slightly differently depending on which chromosome it's on. So they did something "definitely cool," as one genetics professor puts it to the New York Times: dug into data held by three biobanks in the US and Britain.
With the deidentified data of nearly a million individuals at their fingertips, they were able to zero in on 1,225 individuals with rare chromosomal variations—having either an extra or missing X or Y. That led them to this finding, which was published Monday in PNAS: "Increased Y chromosome dosage conferred a larger effect on height than increased X chromosome dosage," suggesting the Y-linked SHOX gene boosts height more than its counterpart on the X chromosome.
The underlying mechanism involves gene silencing, senior author Matthew Oetjens tells the Times. In females, most genes on one X chromosome are turned off, with the exception of those near the tip. The SHOX gene is located close to that end, so it does have some impact. In males, both the X- and Y-linked SHOX genes are fully active, delivering a slightly higher dose. That difference, the authors say, accounts for an estimated 22.6% of the average male-female height gap. Male sex hormones are believed to account for the bulk of the rest. (This content was created with the help of AI. Read our AI policy.)
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