KANNAPOLIS, N.C. - Researchers at the UNC-CH Nutrition Research Institute have linked a gene that could be a genetic cause for some cases of male infertility.

Amy Johnson found that a genetic variant is associated with human sperm motility, and between 5-10 percent of men are affected.

Male infertility affects 15 of every 100 couples wordlwide who have been unable to conceive children.

The findings were published in the journal PLoS One which is from the Public Library of Science.

“The study is exciting,” Johnson said, “because we found that sperm from men who have this genetic difference look similar to sperm produced in mouse models that completely lack the choline enzyme.”

Johnson is  a postdoctoral research associate working under Steven Zeisel, M.D., Ph.D., the institute’s director.

The variant, called a single nucleotide polymorphism (SNP), “commonly occurs within the gene for human choline dehyrdogenase (CHDH) and can influence the amount of choline required in an individual’s diet. Choline, a nutrient used to form cell membranes, is found in eggs, meats and wheat germ, among other foods,” UNC noted.

The CHDH is associated in chages in sperm cell structure and motility, lower energy levels, and has been found to be true in both mice and humans.

“Often the cause of a man’s infertility is unknown,” Johnson said. “But we now have evidence that the CHDH SNP may play a role in some of these cases. This is encouraging because we know that dietary interventions can improve sperm energy levels and motility in mice.”

UNC plans further studies to see if choline nutrient supplements can improve sperm function in men with CHDH variations.