Oberlé I, Drayna D, Camerino G, White R, Mandel J L
Proc Natl Acad Sci U S A. 1985 May;82(9):2824-8. doi: 10.1073/pnas.82.9.2824.
A DNA fragment (named St14) derived from the human X chromosome reveals a small family of related sequences that have been mapped to the Xq26-Xq28 region by using a panel of rodent-human somatic cell hybrids. The probe detects in human DNA digested by Taq I a polymorphic system defined by a series of at least eight allelic fragments with a calculated heterozygosity in females of 80%. With Msp I, we found three additional restriction fragment length polymorphisms, each of them being defined by two alleles. These polymorphisms are also common in Caucasian populations. The genetic locus defined by probe St14 has been localized more precisely to the distal end of the X chromosome (in band q28) by linkage analysis to other polymorphic DNA markers. The results obtained suggest that the frequency of recombination is distributed very unevenly in the q27-qter region of the X chromosome, with a cluster of seven tightly linked loci in q28 showing about 30% recombination with the gene for coagulation factor IX located in the neighboring q27 band. Probe St14 reveals one of the most polymorphic loci known to date in the human genome, and 17 different genotypes have already been observed. It constitutes the best marker on the X chromosome and should be of great use for the genetic study of three important diseases: hemophilia A, mental retardation with a fragile X chromosome, and adrenoleukodystrophy.
一个源自人类X染色体的DNA片段（命名为St14）揭示了一个相关序列的小家族，该家族已通过一组啮齿动物-人类体细胞杂种被定位到Xq26 - Xq28区域。该探针在经Taq I消化的人类DNA中检测到一个多态系统，该系统由一系列至少八个等位基因片段定义，计算得出女性的杂合度为80%。使用Msp I时，我们发现了另外三种限制性片段长度多态性，每种多态性均由两个等位基因定义。这些多态性在白种人群体中也很常见。通过与其他多态性DNA标记进行连锁分析，由探针St14定义的基因座已更精确地定位到X染色体的远端（q28带）。所得结果表明，重组频率在X染色体的q27 - qter区域分布非常不均匀，q28中有七个紧密连锁的基因座簇，与位于相邻q27带的凝血因子IX基因显示出约30%的重组。探针St14揭示了人类基因组中迄今为止已知的最多态性基因座之一，并且已经观察到17种不同的基因型。它是X染色体上最好的标记，对于三种重要疾病的遗传研究应该非常有用：甲型血友病、脆性X染色体所致智力障碍和肾上腺脑白质营养不良。
