The frequency and distribution of aberrant chromosomal RM couples
The First Affiliated Hospital of Xi’an Jiaotong University is a tertiary referral teaching hospital. 5680 recurrent miscarriage couples came to the Reproductive Medicine Center from January 2008 to December 2018 as shown in Figure 1. The flow chart shows that 954 couples had not completed the etiology screening evaluation and 1491 couples had not peripheral karyotype test of both female and male, so the remaining 3235 couples had complete karyotype analysis results. There are 121 couples of abnormal chromosomal karyotypes in 3235 couples with complete results (including abnormalities of either the female or the male and excluding chromosomal normal polymorphisms) with the abnormality rate of 3.74% (121/3235). Among 121 couples with abnormal chromosomal karyotypes, 101 cases were structural abnormalities (3.12%, 101/3235), and 20 cases were abnormal numbers (0.62%, 101/3235).
As shown in Figure 2A, 101 structural abnormal cases included 46(38.02%) with balanced translocation, 42(34.71%) with inversion, 13(10.74%) with Robertsonian translocation, and 20(16.53%) cases had the numerical chromosome aberrations. In order to further illustrate whether the chromosomal abnormality comes from the female or the male, we noticed that 75 female and 46 male were with chromosomal abnormality among 121 RM couples, and the distribution of abnormal chromosome types in female and male respectively can be shown in the Figure 2B. During the following-up of 121 chromosomal abnormal couples with recurrent miscarriage, 55 couples were pregnant and 66 couples were not pregnant merely by medical expectant management through natural conception or intrauterine insemination without IVF/PGD as in the flowchart of figure 1. The proportions of the four types of chromosomal abnormalities among pregnant and non-pregnant carriers was shown in Figure 2C and 2D. The two groups had no statistical difference in the four-type abnormal distribution by chi-square test (p=0.31).
In the 55 carriers, the most common balanced translocation chromosome was No. 8 (15%) while the most rare types were No. 10, 11, 16, 17, 19, 20, X and Y (0%) shown in the Figure 3A. The inversion of chromosome 9 accounted for 86%, the next was No.1 (9%) and No.6 (5%) as showed in the Figure 3B.