Camargo M, Cervenka J
Hum Genet. 1984;67(1):37-47. doi: 10.1007/BF00270556.
High resolution chromosome analysis and bromodeoxyuridine (BrdUrd) incorporation have been applied to study patterns of chromosomal replication (inactivation) in two cases of unbalanced X-autosome translocations, seven cases of X and Y chromosome rings or fragments, and five cases of dicentric isochromosomes (Xq). Our results indicate the following: (1) In (X-A) translocations, detailed replicational analysis of the translocated autosomal segment is informative. Absence of "spreading effect" and partial-incomplete spreading effect are the most common observations. (2) Sex chromosome derived fragments and rings can be differentiated based on their replicational features. (3) Dicentric isochromosomes (Xq) can be classified based on intercentromeric distances, replicational asynchrony, and centromere inactivation. (4) A correlation between intercentromeric distance and degree of 45,X mosaicism was observed in dicentric "i(Xq)" chromosomes. Evidence for spreading effect based on our results and on the review of the literature has been critically analyzed and general rules in evaluating spreading effects (SE) proposed. The cytologic detection of active regions on the late replicating X chromosome and the inactivation capacity of the juxtacentromeric region of Xp is evaluated. It is proposed that centromere suppression and underreplication are related phenomena. Finally, the analysis of informative replicational stages is emphasized and the application of their analysis in basic and clinical cytogenetics demonstrated.
高分辨率染色体分析和溴脱氧尿苷（BrdUrd）掺入技术已被用于研究两例不平衡X-常染色体易位、七例X和Y染色体环或片段以及五例双着丝粒等臂染色体（Xq）的染色体复制（失活）模式。我们的结果表明：（1）在（X-A）易位中，对易位常染色体片段进行详细的复制分析是有意义的。最常见的观察结果是不存在“扩展效应”和部分-不完全扩展效应。（2）性染色体衍生的片段和环可以根据其复制特征进行区分。（3）双着丝粒等臂染色体（Xq）可以根据着丝粒间距离、复制不同步和着丝粒失活进行分类。（4）在双着丝粒“i（Xq）”染色体中观察到着丝粒间距离与45,X嵌合体程度之间的相关性。基于我们的结果和文献综述，对扩展效应的证据进行了批判性分析，并提出了评估扩展效应（SE）的一般规则。评估了晚期复制X染色体上活性区域的细胞学检测以及Xp近着丝粒区域的失活能力。有人提出着丝粒抑制和复制不足是相关现象。最后，强调了对信息丰富的复制阶段的分析，并展示了其在基础和临床细胞遗传学中的应用。
