THURSDAY, Sept. 30 (HealthDay News) -- The cause of male
infertility often escapes experts, but scientists have found a
genetic mutation that appears to disrupt sperm production.
"This may be the most frequent single gene defect that is associated with male infertility known to date, with 4 percent of men with unexplained severe spermatogenic failure carrying a mutation," said Kenneth McElreavey, a researcher at the Pasteur Institute in France and a member of the team that made the discovery.
The gene, NR5A1, has been associated with other reproductive
problems, McElreavey noted. "Studies in the last 10 years have
linked mutations involving NR5A1 to defects in the development of
external genitalia in boys," he said. "Last year, we identified
mutations in this gene associated with a range of reproductive
problems in women."
The new study links mutations in the same gene with reduced
sperm count, which can lead to male infertility problems.
Male infertility is believed to account for nearly half of all
infertility cases. Worldwide, about one in seven couples has
problems with infertility and conception, according to the
McElreavey and his colleagues reported the findings online Sept.
30 in the
American Journal of Human Genetics.
The researchers sequenced the gene in 315 healthy men who sought
treatment for infertility because of an unexplained failure to
produce sperm. They found seven men with a severe sperm production
problem who carried a mutation in the gene. The defect was not
found in more than 2,000 samples from a control group, for
The carriers of the mutation, McElreavey said, "may have a
progressive reduction in sperm quality and quantity over time."
However, some men may be affected more than others if the
findings in women -- "some women carriers of the mutations have no
obvious reproduction [defects]," he said -- also hold true in men.
The difference may stem from other genetic or environmental
factors, he explained.
In the future, McElreavey added, those identified as carriers
might be counseled to start a family earlier rather than later, if
suspicions about the progressive nature of the defect bear out.
What's not known is whether other genes regulated by NR5A1 are
also contributing to sperm production problems, he said.
Dr. Robert Oates, a urology professor at Boston University
School of Medicine, described the study as scientifically very
sound but offered some caveats.
The researchers found a link, but not cause and effect, he
pointed out. And, the finding has no immediate practical
application. "There's no commercial test for this [mutation] at
this point," Oates said.
As good as the science is, Oates noted, the finding must be
duplicated by other experts, in scientific fashion.
For now, he said, the finding might help convince some
infertility doctors not to push men to start treatment right away,
without first looking for possible causes of the infertility.
The American Society for Reproductive Medicine has more about
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