Multiple genes control the manufacture of sperm (spermatogenesis). At least 10 of these genes have been recognized on the male (Y) chromosome, and DNA tests on a blood sample may reveal the absence of one or more of these genes. These so-called microdeletions are at the root of the problem and cannot be specifically remedied.
Men with a microdeletion on the Y chromosome will pass this condition to each of their sons (who will inherit the same problem) but to none of their daughters. Other genes, some recognized and others not yet located, are involved in forming sperm and controlling their structure and movement. Some rare genetic disorders are recognized in which a gene(s) mutation may be the cause of sperm that hardly move (immotile sperm). Routine tests for these genes are not yet available.