Apart from:Where? ******* Chernobyl?
And who's saying this because you'll find plenty of reference to this in the pro-trans web, but curiously little serious scientific support for anyone with a third chromasome or a whacky variety beyond XX and XY that has actually lived a meaningful life measured beyond hours and minutes that supports the emergence of a Xim/Xer as anything other than self-professed make believe.
47,XXY (Klinefelter Syndrome or simply XXY) is the most common of the X and Y variations, also known as “sex chromosome aneuploidy” (SCA).
Trisomy X (47,XXX or Triple X Syndrome) affects approximately 1 in 1,000 females. Learn more about this chromosomal variation and its variable symptoms.
47,XYY, sometimes referred to as “Jacob’s syndrome,” affects about 1 in 1,000 males. This variation may produce a wide array of symptoms. Learn more.