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Before the in vitro procedure patients should consider to perform a basic panel of genetic tests. Based on the results obtained it is possible to estimate a possible risk of transferring a disease or a genetic defect to offspring. The most common additionally recommended tests include, among others:
• Karyotype (woman and man)
Karyotype testing is usually the first diagnostic test recommended to both partners. Karyotype is a set of 23 pairs of chromosomes that is present in the cells building a body of each human being. It contains complex genetic information. Karyotype testing involves determination and description of the number and structure of all chromosomes in a given person. It allows to detect possible abnormalities – mainly regarding the chromosomal structure – in healthy people. Such disturbances (called translocations) are usually not associated with symptoms in an adult “carrier”; however, they might contribute to genetic defects in offspring. Karyotype testing should be performed in both partners. It allows to estimate a potential genetic risk in a given couple (especially, such with a positive genetic history, or with a history of miscarriages or reproductive failures). Karyotype testing is performed once in a lifetime.
• Sperm DNA fragmentation test (man)
The test is performed with the TUNEL method that allows to obtain detailed information on analyzed parameters. It allows to examine in detail the quality of genetic material that is transferred by sperm cells. Based on its findings it is possible to predict the efficacy rate for fertilization, pregnancy development and giving birth to a healthy baby. A standard sperm test does not always provide all necessary information that could be used to determine male fertility. Embryos obtained as a result of fertilization of an egg cell with a sperm with an abnormal (high) rate of DNA fragmentation are associated with a poorer prognosis as early as at the stage of a blastocyst (a 5-day embryo). When delivered to the uterus, they attach significantly more poorly, and pregnancies started with such embryos may result in miscarriages, abnormalities and increased susceptibility of offspring to cancer developing. An increased rate of sperm DNA fragmentation is associated, among others, with infections, fever, elevated temperature of the testicular area, cigarette smoking, inappropriate diet, substance abuse, exposure to environmental contamination, as well as the advanced age. Treatment, namely reducing the fragmentation rate, depends on a causative factor. If chromatin damage has been caused by oxidative stress, a change in the lifestyle and a well-balanced diet may improve the DNA damage rate. In case of infections, the use of antibiotic therapy may also improve the fragmentation rate. The efficacy of activities undertaken has to be checked and the genetic material has to be assessed again, 2-3 months after the first analysis.
Abnormal karyotype findings or a high rate of sperm DNA fragmentation may indicate and increased risk of genetic defects in a fetus. In such cases a physician may advise to perform additional diagnostic tests, namely preimplantation tests, PGS or PGD, as part of the in vitro fertilization program.
