For patients undergoing assisted reproductive treatment, chromosomal testing is performed by drawing peripheral blood from the patient prior to the procedure. Common chromosomal abnormalities include chromosomal structural abnormalities and chromosomal polymorphisms. Chromosomal structural abnormalities Chromosomal structural abnormalities include reciprocal translocations, rosette translocations and inversions, with an incidence of 1/100-1/500, 1/900-1/1000 and 0.12%-0.7%, respectively. Reciprocal chromosomal translocations Reciprocal chromosomal translocations: refers to the displacement of a broken fragment formed by the simultaneous breakage of two non-homologous chromosomes to the broken end of the other chromosome and the joining of the chromosomes to form a new chromosome. Genetic risk: Reciprocal translocation carriers are asymptomatic in themselves because there is no gain or loss of genetic material, but there are fertility problems. One of the couples is a reciprocal translocation carrier and can theoretically produce 18 types of gametes, of which one (1/18) is normal, one (1/18) is a balanced translocation carrier, and the rest are abnormal. Chromosomal Roche translocation Chromosomal Roche translocation: is a form of translocation that occurs on proximal mitotic chromosomes (13, 14, 15, 21 and 22). When two proximal mitotic chromosomes break at or near the mitotic site, the long arms of both join together at the mitotic site to form a derived chromosome consisting of the long arm, and the two broken arms form a minor chromosome, which is often lost during division. Genetic risk: If one of the spouses is a Roche translocation carrier, there are six possibilities for the karyotype of the fetus at the time of pregnancy, of which only one is normal, one is a Roche translocation carrier (balanced), and the remaining four are monosomic or trisomic (unbalanced segregating gametes), and such unbalanced gametes often lead to miscarriage or birth defects. Chromosomal inversions Chromosomal inversions: are caused by two breaks on the same chromosome, resulting in pieces that are reversed 180 degrees and then reattached. If the inversion occurs on one arm of the chromosome, it is called an intra-arm inversion, and if the inversion contains the trophoblast region, it is called an inter-arm inversion. Genetic risk: Chromosomal inversions do not result in significant loss of genetic material, so the patient’s phenotype is generally unaffected. In a couple in which one partner is an inversion carrier, there are four possibilities for the karyotype of the fetus at conception, of which only one is normal, one is an inversion carrier, and the remaining two are chromosomally partially monosomal or trisomal. Chromosomal polymorphism Chromosomal polymorphism: In a population, chromosomes are not constant, and various small variations are commonly found in chromosomes. The differences are mainly in the intensity of coloration, morphological structure, and width of banding between homologous chromosomes, and usually have no obvious phenotypic effects or pathological significance. Chromosomal polymorphisms usually refer to the increase or absence of sub-constrictions on chromosomes 1, 9, and 16, the variation in the follower region of group D/G chromosomes (mainly including enlarged follower region and double follower), and the variation in the long arm of Y chromosome. Common types of chromosomal polymorphisms: 1. 1/9/16 variants: 1qh+, 9qh+, 16qh+ 2. Group D/G variants: 13p+, 14p+, 15p+, 21p+, 22p+ 3. Y chromosome variants: Yqh+, Yqh-, inv Y Genetic risk: There is controversy in the literature regarding chromosomal polymorphisms and infertility and pregnancy outcome. In recent years, most of the literature studied with assisted reproduction or donor sperm has concluded that chromosomal polymorphisms have no significant effect on the outcome of assisted conception patients, including implantation rate, clinical pregnancy rate, and early miscarriage rate.