Genetic abnormalities affect sperm production and transportation, causing infertility. Recently, the content of male infertility and its treatment has made it necessary to use genetic diagnostic methods. Among these, the request for tests for the most frequently encountered problems is now among routine examinations. Numerical anomalies in chromosomes disrupt testicular functions, while very small regional losses (microdeletions) in the Y chromosome can cause pauses in the sperm production process. In addition, some single-gene diseases, such as a mutation in the CFTR gene associated with Cystic Fibrosis, are associated with the absence of ducts in the testicles.
Chromosomal Abnormalities:
The frequency of all chromosomal anomalies in infertile men has been reported as approximately 7%. This situation is inversely proportional to sperm concentration. In other words, this rate is the highest in azoospermic (no sperm seen in semen) men (10-15%). In oligospermic (less than normal sperm seen in semen) men, it is seen at a rate of 5%. In men with normal sperm quality, this rate is less than 1%. The most common chromosomal anomaly in infertile men is Klinefelter Syndrome (47 XXY; 46 XY/47 XXY). It constitutes two-thirds of chromosomal anomalies in infertile men. Therefore, in cases of azoospermia not related to obstruction or severe oligospermia, karyotyping, that is, a chromosome test should be performed from a blood sample taken from the patient's arm.
Y Chromosome Microdeletions:
The Y chromosome is what determines the gender as male. Very small losses in some regions on the Y chromosome are called microdeletions. These small losses cannot be detected with standard chromosome tests. More sophisticated genetic tests are used for this. These tests can also be performed on a simple blood sample taken from the arm. Microdeletions are detected in the Y chromosome in 7-10% of azoospermic and severely oligospermic infertile men. These losses, which are generally seen on the long arm of the chromosome, include genes necessary for normal sperm production such as AZF (Azospermic Factor), AZFb and AZFc. The loss in these regions causes the loss of the function coded by their genes, i.e., pauses in sperm production. Men with microdeletions in the AZFc region are only severely oligospermic and sperm can be found from the testicles of many of them with surgical methods. The probability of obtaining sperm is quite low in men with microdeletions in the AZFa and AZFb regions. There is a possibility that men with Y chromosome microdeletions will pass this disorder and its clinical results on to their sons. In the in vitro fertilization procedure to be performed on these patients, genetic diagnosis (PGD) of the embryos before transfer will prevent this situation.
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