Purpose To assess the frequency and types of chromosomal abnormalities in 204 Ukrainian patients with non-obstructive azoospermia and oligozoospermia and 87 men with normozoospermia. Methods Cytogenetic studies were performed on peripheral blood lymphocyte samples of 164 men with oligozoospermia, 40 men with non-obstructive azoospermia and 87 men with normozoospermia attending infertility clinic. Results Chromosomal abnormalities were detected in 17 % of patients with sperm disorders: in 35 % of men with azoospermia and in 12.7 % of men with oligozoospermia. The frequency of chromosomal abnormalities in patients with sperm disorders was significantly higher, than in patients with normozoospermia (P=0.0001). An increase in the incidence of chromosomal abnormalities with the decrease of sperm count was observed. Chromosomal abnormalities were detected in 1.1 % of patients with normozoospermia, 6.5 % of patients with mild oligozoospermia (sperm count 5-15 ×10 6 /ml), 18.4 % of patients with severe oligozoospermia (sperm count <5 ×10 6 /ml) and 35 % of patients with azoospermia. A significant increase in the frequency of chromosomal abnormalities in patients with severe oligozoospermia was observed when compared to mild oligozoospermia (P=0.01). A statistically significant association (P= 0.02) of chromosomal abnormalities and sex chromosome abnormalities (P=0.0001) with azoospermia when compared to oligozoospermia was observed. Conclusions Our results highlight the importance of cytogenetic studies in patients with oligozoospermia (both mild and severe) and non-obstructive azoospermia. The presence of chromosomal abnormalities influences significantly the fertility treatment protocols, as well as provides a definite diagnosis to couples suffering from infertility.

The results of cytogenetic studies of 3414 patients with infertility (1741 women and 1673 men) were analyzed retrospectively to estimate the frequency and types of chromosomal abnormalities in infertile patients. Chromosomal abnormalities were detected in 2.37% of cases (81/3414), corresponding to an abnor mality frequency of 2.79% among men and 1.95% among women. Balanced structural chromosomal rear rangements were predominant in the studied group, constituting 80.2% of all chromosomal abnormalities. Gonosomal abnormalities comprised 23.5% of the detected chromosomal pathology (19/81) and were pre sented by gonosomal aneuploidies in 84% of cases (16/19) and structural rearrangements of chromosome Y in 16% of cases (3/19). The frequency of sex chromosome low level mosaicism was 0.55%. Our results high light the importance of cytogenetic studies in patients with infertility before the start of infertility treatment programs with assisted reproduction techniques, since the detection of chromosomal abnormalities makes it possible to identify infertility etiology as well as change the treatment approaches.

Balanced chromosomal translocations do not normally have phenotypic manifestation, but lead to increased risk of infertility, miscarriage and live-birth of chromosomally unbalanced offspring in carriers. The risk assessment of such outcomes in carriers of rare chromosomal abnormalities is complicated since limited information is available on the frequencies of unbalanced sperm and embryo formation. Therefore, the aim of this study was to investigate the amount of normal/balanced and unbalanced sperm and embryos of a rare non-Robertsonian chromosome fusion carrier with karyotype 45,XY,der(5;15)(q35.3;q10). Cytogenetic analyses of peripheral blood lymphocytes, multicolour fluorescence in situ hybridization on sperm sample, trophectoderm biopsy, and preimplantation genetic diagnosis by array comparative genomic hybridization were performed. The most frequent type of meiotic segregation was alternate (53% in sperm and 66.7% in embryos), followed by adjacent (44% in sperm and 33.3% in day-5 embryos). Additionally, 3:0 segregation was detected in sperm with a frequency of 2.6% and not detected in day-5 embryos. Results of sperm segregation analysis in rare rearrangement carriers are valuable for genetic counselling in assisted reproduction.

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