Genetic Causes of a Male Infertility Disorder Revealed

A new study gives insight to the genetic alternations that cause severe spermatogenic failure (SSF).  Severe spermatogenic failure is a genetic condition that causes low sperm count and infertility.  The study published by Cell Press in the American Journal of Human Genetics reveals which alterations are the greatest risk factors for the disease, and they could be applicable in genetic counseling for assisted reproduction.  This study, first of its kind for the Y chromosome, helped researchers determine that two types of deletions account for 8% of severely low sperm count.



The most common known genetic causes of SSF are deletions in the Y chromosome's AZFc region.  Although six deletions in the AZFc region were reported, it was not known how prevalent they were in the general population or how the deletions increased the risk of the disorder.  Steve Rozen of Duke-National University of Singapore Graduate Medical School and his collaborators screened for the six deletions in more than 20,000 men from India, Poland, Tunisia, Vietnam, and the United States.  Two deletions were found, for the most part, to be largely responsible for the AZFc region's contribution to SSF.  The most common deletion, gr/gr was found in 2% of men, 2% of cases and doubled the risk of SSF.  The rare b2/b4 deletion found in less than 1% of men, increased the risk of SSF by a factor of 145 and accounted for about 6% of cases.  These findings can be helpful in genetic counseling when a man with the deletions seeks assisted reproduction to have a child.  This study will also lead to more clinical research regarding these deletions.  I think the new discoveries in genetics will lead to an increase in genetic counseling for individuals.