A recent study from the UK of more than 207,000 adult men revealed something surprising - about 1 in 500 men did not have the typical XY sex chromosomes, but instead have XXY (Klinefelter Syndrome) or XYY. And only 23% of those with XXY and 0.7% with XYY actually knew it or this was recorded in their medical records!
This means that most of the men did not have any obvious reason to do genetic screening. The men, all of European ancestry and between the age of 40 and 70 years, participated in the UK Biobank (so these adults were considered healthier than the general public).
One finding is that the XYY and XXY men tended to have more health problems than typical XY men, more lived alone or without a partner than XY men, and more reported loneliness.
Some of the XXY men had received the XXY diagnosis during adolescence for delayed puberty, or later for infertility or lower testosterone levels. Other features can include tall adult stature, high body fat percentage, poor muscle tone, low bone mineral density, and increased risks of neurocognitive disability, psychoses, and disorders of personality.
On the other hand, XYY men tended to have normal sexual development and fertility. Features can include being tall, scoliosis, learning difficulties, poor muscle tone, increased central fat (abdominal fat), seizures, asthma, and emotional and behavioral problems (e.g., attention deficit disorder).
But what was surprising was that both XXY and XYY men were similarly at higher risk for several conditions: type 2 diabetes, venous thrombosis, pulmonary embolism, and chronic obstructive pulmonary disease. [See tables in study.]
Even though XXY and XYY can result in learning difficulties, also note that while 40.4% of XY men had graduated college, 16.3% of XXY, and 20.2% of XYY also had. In other words, there are heightened risks of certain problems (including diseases), but that doesn't mean it definitely results in problems. As the researchers point out: there are increased risks of "potentially preventable diseases", including the "metabolic and vascular diseases".
One question comes to mind: If there is no obvious reason, should a person (even babies) receive genetic screening to see what their sex chromosomes are? Does everyone really want to know? Is there really a need to always know by the person or others? Employers? To be labeled by insurance companies? Especially if there is no obvious reason to test.
Around one in 500 men could be carrying an extra X or Y chromosome—most of them unaware—putting them at increased risk of diseases such as type 2 diabetes, atherosclerosis and thrombosis, say researchers at the universities of Cambridge and Exeter. ...continue reading "Extra Sex Chromosomes In Men More Common Than Many Realize"