Introduction: Robertsonian translocation (RobT) is the central fusion of the long arms of two acrocentric
chromosomes, leading to 45 chromosomes in humans. The most common ones are rob(13;14)
and rob(14;21) (91%). Other types of RobT are so-called rare cases. In the general population
RobTs occur with a frequency of approximately 0.123%, but among men with reproductive
failure this value rises 9-fold. Infertility in RobT carriers is associated with the formation of
unbalanced spermatozoa resulting from segregation of the chromosomes involved in trivalent
during the meiotic prophase. In spermatozoa of many RobT carriers an increased level
of chromosomal aneuploidy is observed.
Materials and Methods: We examined the hyperhaploidy level of chromosomes 7, 9, 18, 21, 22, X and Y in spermatozoa
of 6 RobT unrelated carriers: two carriers with rare rob(13;15), one with rare rob(13;22), and
three of the common rob(13;14). Results were compared with the control data from a group
of 7 fertile men with a normal karyotype. Fluorescent in situ hybridization (FISH) was applied.
Results: We found an increased level of sperm aneuploidy regarding at least one of the analyzed
chromosomes in each of the carriers, while in rare RobTs interchromosomal effect (ICE) was
observed. Meiotic segregation pattern of a rare rob(13;15) carrier revealed the 76% of normal
/balanced spermatozoa.
Disucussion: Due to the relatively high population frequency of RobTs, their influence on reproductive
failure, hight risk of imbalancement in prenatal diagnosis (7%), and small amount of data for
rare RobTs, each newly characterized case is valuable in genetic counseling.