KANNAPOLIS — Fifteen of every 100 couples in the world who want to have children find it difficult or impossible to conceive, according to the UNC Nutrition Research Institute in Kannapolis.
In about half those couples, the difficulty results from the male partner’s infertility.
Now researchers at the Nutrition Research Institute at the N.C. Research Campus have found a possible genetic cause for some incidences of male infertility.
A study led by Dr. Amy Johnson, a postdoctoral research associate working under the direction of institute director Dr. Steven Zeisel, has found that a genetic variant, called a single nucleotide polymorphism or SNP, is associated with human sperm motility. Between 5 percent and 10 percent of men are affected by this variant.
The SNP commonly occurs within the gene for human choline dehyrdogenase and can influence the amount of choline someone needs to eat. Choline, a nutrient used to form cell membranes, is found in eggs, meats and wheat germ, among other foods.
The findings appeared in the April 27 issue of the journal PLoS One, published by the Public Library of Science. Go to http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0036047 . “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.”
In both mice and humans, the variant is associated with changes in sperm cell structure and motility, as well as lower energy levels.
The cause of a man’s infertility is often unknown. But researchers now have evidence that the genetic variant may play a role in some of the cases, Johnson said.
“This is encouraging because we know that dietary interventions can improve sperm energy levels and motility in mice,” she said.
Future studies will explore whether ingesting more choline can improve sperm function in men with the genetic variation.
The N.C. Research Campus includes branches of eight universities studying health, nutrition and agriculture on the molecular level, as well as more than one dozen private companies. The campus is a public-private partnership founded by David Murdock, chairman of Dole Food Co.