Monday, June 05, 2006

Quality of Men's Sperm Falls With Advancing Age (2006 June 5)

Quality of Men's Sperm Falls With Advancing Age, Study Finds2006-06-05 17:00 (New York)

By Todd Zeranski
June 5 (Bloomberg) --

The genetic quality of men's sperm decreases with advancing age, raising the risk of dwarfism andreducing the chances of a normal pregnancy, a new study publishedby the National Academy of Sciences of the USA said.

``We're just opening the door to this new line of research,'' Dr. A.J. Wyrobek, a senior biophysicist at theLawrence Livermore National Laboratory in California and co-headof the study, said in a telephone interview.

Men who delay reproduction increase the risk of passing certain genetic diseases onto their children, at a time when ithas become more socially acceptable to delay having children, Dr.Wyrobek said.

Since 1980, U.S. birth rates increased as much as 40 percentfor men 35-49 years old, and decreased as much as 20 percentamong men younger than 30. Research had already found the spermof aging men is less fertile and more prone to spontaneousabortion.

He said prior research has found a correlation between increasing age and 20 genetic defects, and the new researchsought to uncover whether the cause for two abnormalities --dwarfism and Apert syndrome -- was found in men's sperm.

A parallel genetic analysis of men's sperm found a higher incidence of Apert syndrome, which results in severe deformity inthe face and skeleton, among inner-city males in Baltimore, Dr.Wyrobek said. He said scientists did not yet know whether factors such as diet, socio-economic level or ethnicity caused the deformity.

DNA Ages Differently

The study also found that, unlike women, aging men were not more likely to have chromosomal duplications or losses that causegenetic diseases such as Down's syndrome. Scientists used the latest technology to study the breakupof DNA in sperm. While it was generally found that aging men haddeclining sperm quality, individual variations abounded, with some older men having sperm of higher genetic quality than someyounger men. ``There may be men that have multiple different risks,'' Dr.Wyrobek said. The study group was comprised of 97 healthy, non-smoking men from 22 to 80 years of age.

Story illustration: For the National Academy of Sciences Website, see http://www.nasonline.org/site/PageServer

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