Objective: To determine the prevalence of chromosomal aberrations in infertile couples undergoing in vitro fertilization (IVF). Design: Cytogenetic analysis of peripheral blood lymphocytes in the group of patients undergoing IVF. Detection of chromosomal aberrations in the fetuses after IVF. Setting: Department of Medical Genetics and Fetal Medicine, Medical Faculty, Palacký University and the University Hospital, Olomouc. Methods: Cultivation of peripheral blood lymphocytes or fi broblasts of amniotic fl uid. Using fl uorescent in situ hybridization in cases of mosaicism. Results: Out of 638 patients undergoing treatment for male or female infertility, 595 had normal karyotype and 43 (6.8%) had abnormal karyotype. There were detected 9 (1.4%) cases of balanced chromosomal rearrangements, 2 (0.31%) cases of deletion of Y chromosome, 2 (0.31%) cases of inversion, 2 (0.31%) cases of marker chromosome, 5 (0.78%) cases of gonosomal aneuploidy (47,XXY) and 23 (3.65%) cases of gonosomal mosaicism – out of the 22 (3.5%) cases of low-level mosaicism. In the small group of pregnant patients after IVF investigated for the risk of genetic disorders included in our study (n=60) the frequency of chromosomal abnormalities was 9 (15%). Conclusions: Our data show that a high number of infertile couples is affected by chromosomal aberations which occur more frequently in females than in males. It is caused by high frequency of low-level gonosomal mosaicism in the group of infertile women. Chromosomal analyses are highly recommended before each IVF procedure.

        Key words: chromosomal abnormalities, infertility, in vitro fertilisation