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Male Infertility may be Caused by Epigenetic Abnormalities

Rebecca Z. Sokol, M.D., M.P.H.
University of Southern California, Keck School of Medicine
NIEHS Grant P30ES007048

In the first report of its kind, NIEHS-supported researchers at the University of Southern California suggest abnormalities in DNA methylation may be an underlying cause of male infertility. They found increased methylation at many sites on the DNA of poor quality sperm.

About four million couples in the U.S. are infertile and in approximately 40 percent of these cases, the man is infertile with the underlying cause of the infertility being unknown. During germ cell maturation leading to functioning sperm, germ cells undergo extensive epigenetic reprogramming. The researchers hypothesized that disruption of one or more of these processes may lead to abnormal sperm incapable of fertilization.

The team studied semen samples from men attending an infertility clinic determining concentration, motility, and morphology. The researchers next measured DNA methylation on purified sperm from the same samples. They found that sperm DNA from men with low sperm counts or abnormal sperm had higher levels of methylation than DNA from normal sperm.

The epigenetic irregularities were present in a high proportion of genes that were studied. The team will continue its research to try to determine what is causing these changes in methylation of sperm DNA with hopes to someday prevent certain types of male infertility.

Citation: Houshdaran S, Cortessis VK, Siegmund K, Yang A, Laird PW, Sokol RZ. Widespread epigenetic abnormalities suggest a broad DNA methylation erasure defect in abnormal human sperm. PLoS ONE. 2007 Dec 12;2(12):e1289.

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Last Reviewed: February 06, 2008