New mechanism of partial duplication and deletion of chromosome 8: A case report

BACKGROUND: During meiosis, the recombination of homologous chromosomes produces some new heritable mutations, which are the basis of biological evolution and diversity. However, when there is pericentric inversion of chromosomes, unbalanced gametes will be formed in the process of germ cell meiosis. CASE SUMMARY: A 23-year-old pregnant woman at 25 wk of gestation wanted to terminate her pregnancy due to fetal chromosomal abnormalities. She had no exposure to toxic or hazardous substances before and during pregnancy, no history of medication usage during pregnancy, and she underwent cystectomy of ovarian cysts in 2017. On the second day of the 16(th) week of gestation, non-invasive prenatal testing showed chromosome 8 copy number variation. Following genetic counseling, her pregnancy was terminated. CONCLUSION: Recombinant offspring chromosome is rarely seen when the inversion segment is shorter than one-third of the chromosome length. In terms of the mechanism of chromosome 8 duplication/deletion occurrence, attention should be paid to the production of unbalanced gametes by the pairing of homologous chromosome during meiosis, and the possibility of mitotic recombination exchange as well.