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Genetic Testing of Male
Infertility
Specific gene mutations are known to adversely affect testicular function and the production of sperm and thus to have an impact on male fertility. For this reason, the Laboratory for Male Reproductive Research and Testing, Scott Department of Urology, Baylor College of Medicine, has developed a program designed to detect such genetic abnormalities. Genetic factors may interfere with the reproductive processes by affecting either the number or quality (or both) of sperm production and may affect the structure or function of the male reproductive tract. Genes are encoded in DNA located in chromosomes, and genetic testing examines both the number and structure of the chromosomes, as well as the analysis of specific genes. Normal humans have 46 chromosomes that exist as 23 matched pairs. One of these pairs determines the sex of the individual, with males possessing one X and one Y chromosome. In contrast, women have two X chromosomes. At this time, only a limited number of genes are available for diagnosis. The identification of any genetic defect provides important, and possibly definitive, information about the cause of male infertility. In addition, patients who are considering intracytoplasmic sperm injection (ICSI) can be counseled about the risk of passing on genetic defects to their offspring. Detection of any of these genetic abnormalities will allow us to better diagnose and treat causes of male infertility. The Laboratory for Male Reproductive Research and Testing, in conjunction with the Kleberg Cytogenetics Laboratory, is able to test for: 1. Y Chromosome Abnormalities $305.00 The Y chromosome contains some important genetic information required for the formation and function of the testes. There are genes on the Y chromosome that affect the production of sperm by the testes. Research has shown that between 10%20% of males presenting without sperm in the ejaculate carry deletions of Y chromosome DNA. A smaller, but significant, percentage of men with very reduced sperm counts (approximately 5%) also carry similar deletions. The identification of such deletions provides a diagnosis in these patients. In addition, patients carrying Y chromosome deletions and considering ICSI can be counseled as to the risk of infertility in their male offspring. 2. Cystic Fibrosis Gene Mutations With 5T Variance Analysis $300.00 Cystic fibrosis (CF) is the most common life-threatening autosomal-recessive inherited disease in the white population, with a carrier frequency of 4% (1 in 25) and affecting approximately 1 in 2,000 live births. Patients with symptomatic CF present with progressive lung disease and pancreatic abnormalities. Most people have two normal copies of the CF gene, while patients with CF have severe abnormalities of both copies. Mutations of the CF gene are associated with some male reproductive tract abnormalities, such as absence of the vas deferens (the tubes involved in sperm transport from the testicles to the exterior). It has recently been discovered that 80% of men with bilateral absence of the vas deferens possess abnormalities of the CF gene (not to be confused with having CF). Once again, patients with absence of the vas deferens usually have no associated medical problems and are otherwise well, and they often present only because of their infertility. In addition, recent studies suggest that men with otherwise unexplained decreased sperm counts may have an increased presence of CF gene abnormalities. Identification of these findings will help determine choices for treatment, as well as estimating the risk of transmitting CF to offspring. 3. Karyotyping and High-Resolution Chromosomal Banding $500.00 The karyotyping and high-resolution chromosomal banding analysis examines both the number and the structure of the chromosomes through microscopic examination and analysis. This test can provide information about whether extra chromosomes are present, whether a chromosome has been lost, whether the information on the chromosomes has been rearranged, or whether large deletions of DNA are present. Abnormalities in the number of chromosomes or the arrangements of genes on the chromosomes can influence male fertility. Identification of these abnormalities may provide a diagnosis, as well as provide implications for treatment. These genetic tests are offered through the Laboratory for Male Reproductive Research and Testing at the Scott Department of Urology, Baylor College of Medicine, located at 6560 Fannin, Suite 2100. Directors of the Laboratory are Larry I. Lipshultz, M.D., and Dolores J. Lamb, Ph.D. Additional information on these tests can be provided during your office visit.
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Division
of Male Reproductive Medicine and Surgery
Scott Department of Urology
Baylor College of
Medicine
Scurlock Tower
6560 Fannin Street,
Suite 2100
Houston, TX 77030
Phone: (713) 798-6163
Fax: (713) 798-6007