The genetic causes of infertility are not well understood, while they seem quite frequent. We found that mutations of a gene, NANOS1, are possibly among the causes of human male reproduction failure, as they are in the fruit fly. Depending on location within the gene, these mutations can cause a complete lack of germ cells in testes or abnormal spermatozoa. This is the first report describing an association of NANOS1 gene mutations with a human disease. More studies are needed however, to uncover whether testing of NANOS1 gene mutations could be relevant for diagnosis of infertile couples. (By Dr. Jadwiga Jaruzelska, http://jmg.bmj.com/content/early/2013/01/11/jmedgenet-2012-101230 )