Holden J J, Wang H S, White B N
Am J Med Genet. 1984 Jan;17(1):259-73. doi: 10.1002/ajmg.1320170118.
We present our strategy and progress towards the identification of rare restriction fragment length variants (RFLVs) segregating with the fragile-X syndrome. DNA from a carrier mother and two retarded sons was digested with 7 restriction endonucleases and Southern blots were probed with cloned unique X-chromosomal sequences. Two of 17 cloned segments tested revealed RFLVs between the X-chromosomes of the carrier mother. One of them detected variants using Pvu II and Msp I. The Pvu II and Msp I alleles found on the X-chromosome bearing the fragile-X mutation were not found in 31 and 22 random X-chromosomes, respectively. The other probe detected variants using Pvu II and Taq I. The Taq I allele present on the X-chromosome with the fragile-X mutation was found in 23 out of 25 random X-chromosomes, while the Pvu II allele was not found in 21 random X-chromosomes. One of these probes and two other cloned unique X-chromosome sequences were localized distal to Xq26 by in situ hybridization to prometaphase chromosomes and by probing Southern blots containing DNA from a deleted X-chromosome. These are being used for linkage analysis in an extended family.
我们展示了在鉴定与脆性X综合征共分离的罕见限制性片段长度变异（RFLV）方面的策略和进展。用7种限制性内切酶消化了一位携带者母亲和两个智力发育迟缓儿子的DNA，并用克隆的独特X染色体序列对Southern印迹进行杂交检测。在检测的17个克隆片段中，有两个显示出携带者母亲X染色体之间存在RFLV。其中一个片段使用Pvu II和Msp I检测到了变异。在携带脆性X突变的X染色体上发现的Pvu II和Msp I等位基因，在31条和22条随机X染色体中分别未被发现。另一个探针使用Pvu II和Taq I检测到了变异。在携带脆性X突变的X染色体上存在的Taq I等位基因，在25条随机X染色体中的23条中被发现，而Pvu II等位基因在21条随机X染色体中未被发现。通过对前中期染色体进行原位杂交以及对含有缺失X染色体DNA的Southern印迹进行杂交检测，其中一个探针和另外两个克隆的独特X染色体序列被定位到Xq26远端。这些正被用于一个大家庭的连锁分析。
