To determine the distribution of chromosomes and breakpoint regions in the male carriers of chromosomal balanced translocation, and to explore the influence of breakpoint regions on spermatogenesis.

A total of 87 male patients who underwent G-banding karyotype analysis and were diagnosed as translocation carriers in the Department of Central Laboratory of Women and Children's Hospital, School of Medicine, Xiamen University from January 2015 to December 2021, were included in a retrospective study. The clinical data and testing result of semen analysis and sperm morphology were collected and combined with the literature for comprehensive analysis.

Spermatogenesis dysfunction was discovered in 37 of 87 (42.53%) male translocation carriers. The frequency of translocation varied from chromosome to chromosome, its influence on spermatogenesis was also different. Chromosome 1 occurred 16 times, but chromosome Y and 18 occurred only one time. Spermatogenesis dysfunction was observed in 4 cases. The 4 cases showed sex chromosomes translocation and complex chromosome rearrangement. A total of 122 breakpoint regions were identified. Among them, 14 chromosomal bands occurred 3 or more times. Different breakpoint regions had a different influence on the sperm quality. The carriers of Xq28 breakpoint were azoospermatism. Spermatogenesis dysfunction occurred in 3 of 4 carriers involving band 19q13.

The results indicate genetic heterogeneity on spermatogenesis in the male carriers of chromosomal balanced translocation. Clinical manifestations range from normal to oligozoospermia, asthenozoospermia or even azoospermia. Chromosome 1 is most frequently involved. The translocation of Xq28 has the most serious influence on spermatogenesis. All these carriers are diagnosed with azoospermia.

Karyotyping; Chromosome breakpoint; Balanced translocation; Spermatogenesis dysfunction