Deng H X, Xia J H, Ishikawa M, Niikawa N
Department of Human Genetics, Nagasaki University School of Medicine, Japan.
Jinrui Idengaku Zasshi. 1990 Sep;35(3):245-51. doi: 10.1007/BF01876853.
Parental origin and mechanism of formation of X chromosome structural abnormalities were studied in one each case of dup(X)(pter----p11.4::p22.1----qter), del(X)(qter----p11:), i(X)(qter----cen----qter), and inv dup(X) (pter----q22::q22----pter) using various X-linked RFLPs as genetic markers. Segregation and densitometric analyses on polymorphic DNAs revealed that the dup(Xp) and the del(Xp) are both of paternal origin and the i(Xq) and i dic(X) are of maternal origin. The dup(Xp) had arisen by an unequal sister chromatid exchange and the del(Xp) had occurred through an intrachromosomal breakage-reunion mechanism, both in the paternal X chromosome. The i(Xq) had arisen either through centromere fission of a maternal X chromosome, followed by duplication of its long-arm, or through a translocation between two maternal X chromosomes after meiotic crossing-over. The inv dup(X) arose through sister chromatid breakage and reunion in a maternal X chromosome. These results, together with those of previous studies, suggest that the de novo abnormalities due to events involving centromere disruption arise predominantly during oogenesis, while those due to simple breakage-reunion events occur preferentially during spermatogenesis.
利用各种X连锁限制性片段长度多态性（RFLPs）作为遗传标记，对1例dup(X)(pter----p11.4::p22.1----qter)、1例del(X)(qter----p11:)、1例i(X)(qter----cen----qter)和1例inv dup(X) (pter----q22::q22----pter)的X染色体结构异常的亲本来源及形成机制进行了研究。对多态性DNA的分离和密度分析表明，dup(Xp)和del(Xp)均来自父方，而i(Xq)和i dic(X)来自母方。dup(Xp)是由父方X染色体上姐妹染色单体不等交换产生的，del(Xp)是通过染色体内部断裂-重接机制发生的。i(Xq)要么是由母方X染色体着丝粒分裂，随后其长臂重复产生的，要么是减数分裂交叉后两条母方X染色体之间发生易位产生的。inv dup(X)是由母方X染色体上姐妹染色单体断裂和重接产生的。这些结果与先前的研究结果一起表明，涉及着丝粒破坏事件导致的新发异常主要发生在卵子发生过程中，而由简单断裂-重接事件导致的异常则优先发生在精子发生过程中。
