[Genetic analysis of carriers of complex chromosome rearrangement]

To comprehensively analyze the numbers of involved chromosomes and breakpoints and the clinical phenotypes of the patients with complex chromosome rearrangement (CCR).

We selected 23 745 patients with abnormal fertility seeking medical care in the Center of Reproductive Medicine of Peking University Third Hospital from 2011 to 2015, and analyzed their peripheral blood chromosomal karyotypes using G-banding, C-banding and fluorescence in situ hybridization (FISH).

A total of 28 CCR carriers (0.118%) were detected among the 23 745 patients with abnormal fertility, including 18 males mainly with azoospermia or oligoasthenospermia and 10 females mainly with infertility, recurrent abortion, embryo termination and abnormal birth. Of the 28 cases of CCR, tripartite rearrangement was found in 9 (32.14%), double translocation in 7 (25%) and special translocation in 12 (42.86%). CCR carrier-related chromosomes were all involved but chromosomes 12 and 19, while 2 and 5 were involved most frequently.

At present, the incidence of CCR is low. CCR carriers with normal phenotypes are often found because of reproductive problems, and their low chance of having a normal baby necessitates the use of preimplantation genetic test to improve the rate of live birth. Due to the diversity of the chromosomes and breakpoints involved in CCR, it is crucial to give each CCR carrier precise genetic counseling.