Meiotic segregation patterns and ICSI pregnancy outcome of a rare (13;21) Robertsonian translocation carrier: a case report

(13;21) is an uncommon Robertsonian translocation (RT) with limited information in the literature. Hereby, we assessed the meiotic segregation and interchromosomal effect (ICE) in sperm nuclei from a t(13;21) carrier. The pregnancy outcome following ICSI was also included as reference for physicians and patients. Dual-colour fluorescent in situ hybridization (FISH) was carried out to analyse the segregation pattern of chromosomes 13 and 21, while triple-colour FISH was used to investigate the possible concurrence of ICE. With respect to chromosomal constitutions of 13 and 21, 88.39% of the spermatozoa were normal or balanced due to alternative segregations, and 11.08% showed nullisomy or disomy as a result of adjacent segregations. However, for chromosome 18 and sex chromosomes, the proportion of normal haploids was 98.79%. The rate of disomy was not significantly higher than the controls for either chromosome 18 or X/Y. The rare t(13;21) case exhibited a similar pattern of meiotic segregation as in the common RTs. ICEs were not observed in the current case.