Robertson translocation is an abnormal chromosome structure formed by proximal fusion of either two of the proximal chromosomes (group D chromosomes and group G chromosomes). A Robertson translocation loses the short arms of two chromosomes and their long arms are rejoined at the mitoses to form one derived chromosome with a karyotype of only 45 chromosomes, but because the short arms of group D and G chromosomes are the sites of ribosomal genes, which are abundant in humans, individuals with the loss have no clinical phenotypic changes and are called Robertson translocation carriers. There are 15 types of Roche translocations, with Roche translocations on chromosomes 13 and 14 being the most common, accounting for more than 75%. (1) Homozygous Roche translocations (e.g. 45, XX, rob (21; 21) (q10; q10)) cannot form normal gametes (gametes are 21 deletion, or 21 disomy), and when married to a normal karyotype partner, normal offspring are unlikely to be born (embryos formed are 21 monosomy or trisomy), and sterilization is recommended. (2) Non-homozygous rob translocations (e.g. 45, XX, rob(14; 21)(q10; q10)), during gamete formation, through meiosis, can produce six types of gametes, of which only one is normal and one is a balanced structural abnormality, and after marriage with a normal karyotype mate, six chromosome types of embryos can be formed, including four chromosome imbalanced embryos , one karyotype completely normal embryo, and one karyotype with balanced translocation. Most of the unbalanced embryos will spontaneously abort during development, and a few can gestate to full term and form malformed children. Therefore, for non-homologous chromosomal Roche translocations, the pregnancy is prone to miscarriage stillbirth or stillbirth, but there is also a 1 in 6 chance of having a normal child and a 1 in 6 chance of having a child with a Roche translocation, and a prenatal diagnosis can be used to ensure the birth of a normal child. Pre-implantation genetic diagnosis can also be used to reduce the chance of having a chromosomally abnormal fetus.