Worldwide, as many as one in seven couples struggle with infertility. Scientists, puzzled over why otherwise healthy men and women are unable to conceive a child, may have found an answer at least where men are concerned. On Sept. 30, researchers announced online in the American Journal of Human Genetics that they may have answers for men plagued with infertility. Scientists have discovered that a mutation on a single gene may be responsible for male infertility by causing sperm count to be low.
What is Male Infertility?
A man is considered infertile when he has failed to impregnate a woman after a year or more of frequent and unprotected sexual intercourse. Male infertility has many causes such as abnormally shaped or immobile sperm, illness, injuries, blockages, chronic health problems and lifestyle activities like smoking and obesity. Now it seems a mutated gene can be added to that list.
The Male Infertility Gene
The gene in question with male infertility called NR5A1. This same gene is known to cause other reproductive problems such as abnormal testicular development and ovarian dysfunction. The link between the NR5A1 gene mutation and reproductive problems was first reported in a 2009 study in The New England Journal of Medicine. This study found that a mutated NR5A1 gene was present in women and young girls with premature ovarian failure. Given the results of that stody, scientists theorized that the same genetic mutation could be responsible for infertility in men.
What Causes the Mutation?
The cause of the gene mutation also remains a mystery. There is some thought that environmental toxins and chemicals may be to blame. Of particular interest is the herbicide atrazine. Studies have shown this chemical to cause increased risk of cancers of the reproductive system in humans and animals as well as NR5A1 disruption. Once mutated, the damaged gene can be inherited by any children a man may father.
Mutation May Cause Accelerated Infertility
The study also revealed that men with the mutated gene may have normal fertility at a young age. However, it seems these men have an accelerated loss of fertility, possibly becoming infertile as early as their early 20’s. Certainly by the time these men reach their 30’s, fertility is compromised and many times lost altogether. The ramifications for these men is clear: Men who have the gene linked to male infertility need to have children at a much younger age in order to achieve maximum fertility.
Further Study of Male Infertility Gene Needed
Although researchers have discovered the link between NR5A1 and male infertility, many questions still remain unanswered. While scientists know that the genetic mutation lowers sperm count, the nature of how the sperm are affected is not fully understood. Theories abound including the idea that the mutated gene may cause sperm to be underdeveloped. These malformed sperm can’t become mobile enough to reach an egg. It is also thought that the gene mutation may cause decreased levels of testosterone, which in turn leads to low sperm production.
Ramifications of Discovery of Male Infertility Gene
The discovery of the mutated NR5A1 gene as the cause of male infertility has far reaching ramifications in the world of fertility treatment. Now that the gene has been pinpointed, gene therapies can be developed to help infertile men. This research also renews the promise of a male contraceptive pill, though that may be decades away.
Disclaimer: This article is intended for informational purposes only and is not intended to replace the advice of a physician or other medical personnel.
American Journal of Human Genetics
The New England Journal of Medicine