Prader–Willi syndrome (PWS) is a syndrome that - in some cases - may be considered an intersex variation, although many would say it causes intersex traits rather than being one in of itself. Prader-Willi syndrome affects an estimated 1 in 10,000 to 30,000 individuals worldwide.
Those with this syndrome often have weak muscle tone (hypotonia), feeding difficulties, poor growth, delayed development, speech delay, crossed eyes, poor physical coordination, infertility, sparse pubic hair, short stature, a narrow forehead, almond-shaped eyes, a down-turned mouth, small hands and feet, fair skin, light hair, and delayed or incomplete puberty. They also typically have an insatiable appetite which causes overeating and obesity. Typically, one with this syndrome develops type two diabetes. Sleep abnormalities, behavioral problems, outbursts, and compulsive habits are also common with those who have this syndrome.
Some of the physical symptoms listed above may classify one with this syndrome as physically disabled, while ones affecting mental state/mood may classify one with this syndrome as neurodivergent.
Normally, a fetus inherits an imprinted maternal copy of PW genes and a functional paternal copy of PW genes. Due to imprinting, the maternally inherited copies of these genes are virtually silent, and the fetus therefore relies on the expression of the paternal copies of the genes. In PWS, however, there is mutation/deletion of the paternal copies of PW genes, leaving the fetus with no functioning PW genes, causing this syndrome and its symptoms.