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Genetic alterations responsible for male infertility identified
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Results from an NIH-supported study provide insight as to which genetic alterations may pose the greatest risk for severe spermatogenic failure in men.
“Medically relevant population genetics studies are well established for most of the human genome, but this is the first study of this kind for the Y chromosome,” Steven G. Rozen, PhD, of Duke-National University of Singapore Graduate Medical School, said in a press release. “This study let us determine for the first time that two types of deletions jointly account for 8% of severely low sperm count.”
Rozen and colleagues screened for six recurrent deletions in the AZFc region of the Y chromosome in 20,884 men from five areas: Pune, India; Katowice, Poland; Monastir, Tunisia; several sites in the United States; and Hanoi and Hue, Vietnam.
The researchers wrote that they were able to find four of the six deletions (gr/gr, b2/b3, b1/b3 and b2/b4) during the screening process.
Deletions that affect the AZFc region are known to be the most common genetic cause of severe spermatogenic failure (SSF), which is defined as a sperm count of less than 5 million/mL of semen (in the absence of physical obstruction), the researchers wrote.
Participants included a healthy control group and men with osteoarthritis, rheumatoid arthritis, asthma, hypertension, coronary artery disease, myocardial infarction, hyperlipidemia, stroke, type 2 diabetes or osteoporosis.
According to data, 773 men (3.7%) carried one of the four deletions. The most common deletion was gr/gr (2.4%; 95% CI, 2.2-2.7), followed by the b2/b3 deletion (1.1%; 95% CI, 1-1.3); the b1/b3 deletion (0.1%; 95% CI, 0.064-0.16); and the b2/b4 deletion (0.043%; 95% CI, 0.021-0.085).
“Our study reveals that these two deletions are largely responsible for the AZFc region’s contribution to SSF,” Rozen said in the release. “The immediate clinical use of these findings would be in genetic counseling, especially when a man with one of these deletions is using assisted reproduction to have a child.”
The researchers wrote that a closer look at the human reference sequence for this region is needed to accurately identify regions prone to massive structural change.
Disclosure:This study was supported by the NIH, the Howard Hughes Medical Institute and the Singapore Ministry of Health and Agency for Science, Technology and Research. The researchers report no relevant financial disclosures.
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