Parental Origin of de novo chromosome abnormalities.

利用目标染色体上限制性内切片段长度多态性作为遗传标记，研究了新生染色体异常的亲本来源和形成机制。结果表明：(1)18三体的来源为母系；母体第一次或第二次减数分裂不分离是18三体的优先机制，与21三体的先前结果一致。(2)多余X染色体来源于母系；在所有4例XXXXX或XXXXY患者中，在母体第1和第2减数分裂时出现了3个连续的不间断，这表明在人类中存在控制染色体分裂的基因。(3)短暂性骨髓增生综合征（TMS）患者21三体的起源是一条21号染色体因减数分裂或有丝分裂不分离而发生重复，且21号染色体的异型标记均为“aab”型，提示TMS细胞中21号染色体上的基因为“二体纯合”。(4)除一例i(X)外，所有检查的结构异常的起源都是父系的，这支持了之前的假设，即非罗伯逊结构异常的起源优先是父系的。

Parental origin and mechanism of formation of de novo chromosome abnormalities were studied with the use of restriction fragment length polymorphisms located on target chromosomes as genetic markers. The following results were obtained:(1) The origin of trisomy 18 is of maternal; Nondisjunction at the maternal 1st or 2nd meiosis is the preferential mechanism for trisomy 18, consistent with the previous results for trisomy 21.(2) The origin of supernumerary X chromosomes is of maternal; Three successive nondisjunctions at the maternal 1st and 2nd meioses had occurred in all of four cases of XXXXX or XXXXY examined, suggesting the presence of the gene controlling chromosome division in humans.(3) The origin of trisomy 21 in patients with transient myeloproliferative syndrome (TMS) is the duplication of one chromosome 21 due to either meiotic or mitotic nondisjunction, and the heteromorphic markers of the chromosomes 21 are all an "aab" pattern, suggesting that the genes located on chromosomes 21 in TMS cells are "disomic homozygous".(4) The origin of all structural abnormalities examined are of paternal, except for one case of i(X), supporting the previous hypothesis that the origin of non-Robertsonian structural abnormality is preferentially of paternal.