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Researchers Find Gene Linked to Sperm Motility
by Leigh Ann Woodruff, May 16, 2012
Researchers are increasingly finding genes that are linked to fertility, such as the recent British study that identified a gene in mice that is important in sperm to egg binding. Now, scientists at the University of North Carolina at Chapel Hill Nutrition Research Institute have found a possible genetic cause for some cases of male infertility in humans and published their findings in PLoS One.
Led by Amy Johnson, Ph.D., the study found that a genetic variant, called a single nucleotide polymorphism (SNP), is more common in men with compromised sperm motility (sperm movement). Sperm have to be able to propel themselves and move forward to successfully fertilize an egg.
The SNP commonly occurs within the gene for human choline dehyrdogenase (CHDH) and can influence the amount of choline required in an individual’s diet. The researchers found that sperm from men who have the genetic difference look similar to sperm produced in mice that completely lack the choline enzyme. In both mice and humans, the CHDH variant is associated with changes in sperm cell structure and motility, as well as lower energy levels.
Choline is a nutrient similar to the B vitamins that is used to form cell membranes. Humans obtain choline through their diets; the nutrient is found in eggs, meats and wheat germ, among other foods.
"From the results of this study, we now know that the nutrient choline plays an important role in maintaining sperm function," Dr. Johnson says. "Next, we need to demonstrate that our results hold true in a much larger population of men, as well as to determine whether men suffering from infertility may be helped by increasing the amount of choline the eat."
Researchers already know that dietary interventions can improve sperm energy levels and motility in mice. "Finding out that this gene variation is more common in men who produce sperm with compromised function is just the first step," Dr. Johnson says. "We’re a few steps away from being able to recommend increased choline intake as a treatment for male infertility. We do not know how much choline a man would have to eat in order to improve his sperm function, but that is something we will be investigating in the near future."