UCSF researchers find evidence of faulty DNA repair in some inf...( ng genetic Turek said. That's a lot ...)

ng genetic," Turek said. "That's a lot of people." In addition, other researchers in the past have discovered that certain cancers, including a form of colon cancer, are associated with defective DNA repair. In 1995, the journal Cell published two papers in which the genes responsible for DNA repair in mice were altered to see what happened. The mice developed tumors, as was expected. But the mice also became infertile, which was not expected.

" We wondered if infertile men with failing testicles that had a "look" similar to the testes from the altered mice would also show defective DNA repair," Reijo Pera said. "We asked if the testis tissue of these infertile men showed certain "fingerprints" characteristic of a problem repairing DNA."

The current UCSF study included five men with normally functioning testes and five whose testes made little or no sperm, also called testes failure. Investigators sequenced testes tissue DNA from both groups and found an increased frequency of certain DNA mutations or errors in the group with testes failure. These men had 100-fold higher error rate in their DNA than the men with normally functioning testes, Reijo Pera said.

This small study may help explain some cases of male infertility, but also raises several questions, Turek said. The findings need to be expanded to include many more infertile men to get a feel for the real impact of the research, he said.

Also, given what scientists know about defective DNA repair and cancer, researchers need to pay attention to what the consequences of this might be for infertile couples, Turek said. One concern is the health of pregnancies and children conceived with assisted reproductive techniques, such as intracytoplasmic sperm injection (ICSI) in cases of male infertility due to testes failure. This precise technique helps couples with severe male factor infertility have babies by injecting a single live sperm directly into the center of a human egg. The techniqu
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Contact: Leslie Harris
lharris@pubaff.ucsf.edu
415-885-7277
University of California - San Francisco
31-May-2000

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