为探讨中国人群平衡复杂染色体重排(complex chromosome rearrangements, CCRs)的类型、特征和减数分裂行为及其与生殖异常的关系,采用常规G显带技术对因生育问题就诊的1063对夫妇进行核型分析,并检索中国人群平衡CCR携带者的核型及临床资料进行统计分析。在受检者中检出2例平衡CCR携带者,并从国内外数据库中检索发现的平衡CCR携带者总共124例,3方和4方重排为主要类型,占51.6%,双重相互易位占26.6%,特殊CCR占21.8%。平衡CCR携带者或其配偶自然流产和胚胎停止发育(胎停育)发生率为77.6%,多发性先天畸形(multiple congenital abnormalities, MCA)等不良妊娠发生率为9.7%。三种类型平衡CCR携带者各种妊娠结局发生率的差异具有统计学意义(P<0.05)。对男性CCRs累及的染色体分析发现,累及1号染色体的CCRs多表现为生精障碍,累及8号染色体的CCRs多发生不良妊娠(P≤0.05)。分析CCRs减数分裂染色体分离模式发现,后代的异常核型多来自于邻近-1分离方式(8/12)。发生不对称分离(3:2、4:2和5:3分离)的CCRs中D-G组染色体累及频率相对高(46.2%)。结果表明,平衡CCR携带者不良妊娠风险高,即使正常妊娠也应进行产前诊断。男性平衡CCR携带者生精障碍发生机率高,CCRs累及的染色体对男性携带者生育能力有影响。另外,CCRs携带者减数分裂染色体分离模式也与累及的染色体有关。分析CCRs的类型、累及的染色体和易位片段的大小等因素可针对特定CCR做出更准确的遗传和生育指导。

To examine the type, characteristics and meiotic behavior of balanced complex chromosome rearrangements (CCRs) and their relationship with reproductive abnormalities in Chinese people, karyotype analyses were performed in 1063 couples with reproductive abnormalities using G-banding technology. Additional data were retrieved from a Chinese database and analyzed statistically with the karyotype and clinic data of CCRs. Two CCR carriers were found among the 1063 couples, and in all a total of 124 CCR carriers with the complete information were identified in the karyotype analysis and the database search. Our results showed that simple 3-way or 4-way translocations were the most common types, present in 64/124 (51.6%) of CCRs. Double two-way translocations accounted for 26.6% and exceptional CCRs accounted for 21.6% of total cases. General risk of 77.6% for spontaneous abortions and 9.7% for an abnormal child were calculated based on 339 pregnancies of 124 carriers. Pregnancy consequences could be significantly associated with the type of CCRs. Abnormal pregnancy was frequently associated with CCRs on chromosome 8, while dyszoospermia was frequently associated with CCRs on chromosome 1 among the males. The most frequent mode of segregation was 3:3 adjacent-1 (8/12) in 12 abnormal karyotypes. Short chromosomes (groups D-G) were involved in 46.2% of CCRs showing 3:2, 4:2 and 5:3 segregation ratios. In conclusion, carriers of balanced CCRs have a high risk of an abortion and/or a chromosomally unbalanced child. The incidence of spermatogenic defect in male CCR carriers is high, and male infertility is associated with CCRs. Hence, identifying the types of CCRs, chromosomes involved, translocated segments of chromosomes, etc. will provide crucial information for prenatal diagnosis and genetic counseling for carriers of balanced CCRs.