Abstract: One case of family chromosomal karyotype with complex chromosomal translocation and male infertility was reported. This case is a male, 30 years old, Han nationality, who did not receive contraception for 3 years after marriage. The phenotype and intelligence of the patients were normal, and there were no abnormalities in the external genitalia. No abnormalities were found in the prostate and spermatic vein. There was no history of parotitis or testicular trauma, no history of smoking, drinking history, denial of harmful substances and history of radioactive contact. There were no similar patients in the family, and the secondary sex was normal. The routine semen examination suggested that the active sperm was seldom seen. There were no obvious abnormalities in the serum endocrine examination of the patient. Cytogenetic examination: the patient’s karyotype 46XY, t (10; 18; 21) (q22; p11.2; q11.2). There was no deletion in locus sY84, sY86, sY127, sY134, sY143, sY254 and sY255. His wife’s examination showed no obvious abnormality, and her karyotype was normal. The parents of the patients were not close relatives. Their father’s chromosome karyotype analysis was 46, XY, and Y chromosome microdeletion was normal. The chromosome karyotype of the parent was 46XX, t (10; 18; 21), and the parents of the patient also had a daughter, whose phenotype and intellectual development were normal, chromosome karyotype 46XX, t (10; 18; 21). In this case, the patient’s balance translocation should be inherited by the mother. Because of the normal phenotype of the patient, there was no loss of genetic material, but the abnormal chromosomes might be passed to the offspring, and the proportion of the unbalanced gametes was very high. Through systematic review and review of the cases, it was concluded that the balanced translocation carriers only changed the relative position of the translocation segments on the chromosomes, retained the total number of the original genes, only changed the relative position of the genes on the chromosomes, and had no serious effect on the role of the gene and the development of the individual. The phenotype was normal. The patients were given symptomatic treatment to improve semen quality. It is recommended that pre-implantation genetic screening/diagnosis(PGS/PGD) be performed if necessary. It is to guide married men and women to choose the appropriate childbearing age, avoid unhealthy environmental contacts, and strengthen genetic screening before and after pregnancy, so as to achieve the goal of eugenics.

Key words: Translocation, genetic, Infertility, male, Karyotyping, Pedigree