Modern molecular biology and advanced genetic testing have allowed us to diagnose some infertile men with genetic abnormalities as the cause of their inability to achieve a pregnancy.

3 genetic tests are commonly used in infertility testing:

• Cystic Fibrosis Mutations - In men who are found to be missing either one or both vas deferens by physical examination, there may be a genetic defect (mutation) as the cause. There is a very high incidence (~70%) of cystic fibrosis gene abnormalities in men who are missing both vas deferens (CBAVD) who present with no sperm in their ejaculate. Most of these men are healthy and have no other associated medical problems. A simple blood test can be performed which can detect whether or not the man is a carrier of the abnormal gene. The female may also be tested to see if she is a carrier of the abnormal cystic fibrosis gene. Once both partners have been tested, genetic counseling can be scheduled to discuss the risks of abnormal gene transmission to the offspring.
• Karyotype - Normally, humans have 22 pairs of chromosmes called autosomes that determine height, body stature, eye color, skin color, etc. Humans also have 2 sex chromosomes which determine whether they are male or female. Thus, a normal human has 23 pairs of chromosomes (total 46). Women have 2 "X" chromosomes and men have 1 "X" and 1 "Y" chromosome. A normal female karyotype is 46, XX and a normal male karyotype is 46, XY. Aberrations from a normal karyotype may result in infertility. Some men with a syndrome called Klinefelter's syndrome have an extra "X" chromosome and thus a 47, XXY karyotype. There are some men who have a 46, XX karytype (called XX male syndrome) but no Y chromosome. A karyotype is indicated in all men with no sperm in the ejaculate or men with consistently low sperm counts of less than 5 million sperm / ml.
• Y-Chromosome analysis for microdeletions - Technology in the 1990's has advanced so that we can now determine whether any microscopic pieces of DNA within the Y-chromosome itself are missing. Approximately 10 - 15% of men with azoospermia may have a genetic abnormality to explain the reason for their poor sperm production. This test is very specialized and can only be performed properly by very specialized laboratories. In men with testicular failure, this test should be obtained to determine if a genetic abnormality exists. Since these abnormalities may be passed on to offspring, the results of this test may influence what treatments a couple may choose.