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Genetic Test for Male Infertility
Infertility problems can occur in men. The sperm is produced in the testes, stored in the epididymis (coiled channels surrounding the testis), then transport to the woman via the vas deferens during sexual intercourse.
A variety of conditions which result in defective sperm production or transport may lead to male factor infertility.
Examples:
- Smoking
- Alcohol
- Varicose vein in the scrotum
- Undescended testes
- Genital tract infection
- Surgery
In addition, recent studies have shown that approximately 20% of men with azoospermia (no sperm production) or severe oligospermia (extremely low sperm production) are presented with genetic defects which may be the cause of their infertility. Although their infertility problems may be overcome by using special techniques such as epidermal or testicular sperm aspiration (MESA / TESE) and intracytoplasmic sperm injection (ICSI), detection of these genetic causes of male infertility allows couples to be informed about the potential to transmit genetic abnormalities that may affect the health of their offspring.
The three most common genetic factors known to be related to male infertility are (1) abnormalities in the number of sex chromosomes (karyotype), (2) abnormalities in the structure of the male chromosome (Y-chromosome microdeletions) and (3) cystic fibrosis gene mutations associated with congenital absence of the vas deferens.
1) Sex Chromosome Abnormalities
About 10-15% of men with azoospermia or severe oligospermia may carry a chromosome abnormality. Amongst the various types of chromosomal anomalies which may be responsible for male infertility, the most common form is the Klinefelter syndrome. These male patients carry an extra X chromosome (47,XXY). They are characterized by gynaecomastia, small firm testes and abnormal sperm production. However, it may not be detected until they present with infertility. The couple is at increased risk for recurrent miscarriages and for having children with sex chromosome defects.
2) Y-Chromosome Microdeletions
Another 10-15% of men with azoospermia or severe oligospermia may have small deletions in the genes located on the Y-chromosome which are required for normal spermatogenesis (the process of sperm production). The only known health problem associated with these deletions is impaired sperm quantity and quality. However, the deletion will be inherited through the Y-chromosome (male chromosome) to the potential son who may consequently be infertile.
3) Cystic Fibrosis Gene Mutations
Male patients with azoospermia as a result of being born without two vas deferens frequently carry a mutated gene responsible for cystic fibrosis but do not have the disease itself. Cystic fibrosis is inherited as an autosomal recessive disorder typically characterized by lethal complications of the lung and pancreas. The lethal effect of this gene mutation would be expressed when a person inherits the abnormal recessive gene from both parents. If the cystic fibrosis gene is detected in the male, his wife should have genetic screening. If both of the couple are carriers of the cystic fibrosis gene, there will be a 25% chance of their children inheriting the disease of cystic fibrosis
Genetic Evaluation
Since the hospital presently does not have facilities for these genetic tests, men with azoospermia, or severe oligospermia of sperm count less than 5 millions per ml, or congenital absence of vas deferens who are interested in undergoing assisted reproduction may consider having their genetic screening performed as a private service in the university laboratory. There is at present no treatment for these genetic diseases but preimplantation or prenatal diagnosis may be considered.
If you need further explanation, please feel free to contact our staff.