- What is the Genetic Control Test?
- When is the Genetic Control Test performed?
- What preparation is needed before the Genetic Control Test?
- What is the process of the Genetic Control Test?
- How are the results of Genetic Control Test interpreted?
Male subfertility and hypogonadism (testicular dysfunction) may be due to genetic causes, i.e. hereditary chromosomal abnormalities or acquired chromosomal genetic material impairment. The main genetic tests are the following:
- Caryotype: imaging of all male chromosomes, identification of numerical abnormalities (higher or lower number of chromosomes, which may be up to 46 in overall) and detection of structural abnormalities (gene deficiencies, duplications, mutations, translocations).
- Cystic Fibrosis: hereditary disease which is a problem when the man inherits the ‘defective’ gene from both parents. In this case there may be agenesis of the vas deferens, i.e. absence of ejaculatory ducts. However, testes produce normally sperms, which cannot though exit. On the contrary, when the man has inherited the pathological gene from only one parent, the likelihood of presenting cystic fibrosis or absence of the vas deferens is 25%.
- AZF Micro-deficiencies: Chromosome Y is present only in the male and is responsible, among others, for inducing testicular production of sperm cells. More specifically, there are three loci at chromosome Y, which control the induction of sperm production. The most important of the three is locus A; severe impairment in locus A causes azoospermia, which cannot be cured. The next important region is locus B; sever impairment in locus B may cause moderate to severe reduction in the number of sperm cells. Lastly, locus C is the least important; impairment in locus C causes mild to moderate oligospermia.
DNA fragmentation test: Direct DNA impairment may be due to the presence of free radicals -as happens in the cases of idiopathic (unexplained) infertility, varicocele, testicular neoplasia, chemotherapy for other reason etc.
Main indications for Male Genetic Testing are idiopathic (unexplained) infertility with azoospermia and/or severe oligospermia (less than 5 million sperm cells/ml semen). In addition, the above testing is conducted when the family history of the male presents cases of hypogonadotropic hypogonadism (hypothalamic or pituitary dysfunction), chromosomal mutations and syndromes related to male infertility, such as syndromes Klinefelter, Kallmann, Prader Willi, Young etc. The therapist physician has always to ask about the above. Lastly, Genetic Testing is conducted when there is unexpected male sexual differentiation (deficiency in male features, such as voice, hair growth, muscle mass etc).
No special preparation is needed, as the procedure is that of a simple blood test. Food or fluid consumption does not affect the result; however, given that Genetic Control usually includes other tests as well, it would be better to avoid food and fluid intake (except water) eight hours before blood sampling.
The process is simple: obtaining peripheral venous blood (from the arm) at specialized Molecular Biology Laboratories. As with every blood sampling, you should gently press the puncture site with dry cotton without rubbing to avoid causing hematoma.
Genetic Testing results may concern various male fertility parameters. For example:
- excessive number of a specific chromosome, as in the case of Klinefelter syndrome.
- structural abnormality of some chromosome that may result even in azoospermia (e.g. gene micro-deficiencies in chromosome Y).
- DNA fragmentation >30% drastically reduces the likelihood of a couple to conceive spontaneously.
The results of the above testing have to be taken into account together with other parameters concerning the couple, such as the female partner’s age and results of supplementary male tests, before choosing the appropriate therapeutic fertility approach of the couple.