Davies K E, Mattei M G, Mattei J F, Veenema H, McGlade S, Harper K, Tommerup N, Nielsen K B, Mikkelsen M, Beighton P
Hum Genet. 1985;70(3):249-55. doi: 10.1007/BF00273451.
One of the commonest forms of X-linked mental retardation is associated with a fragile site at Xq27 on the human X chromosome which can be visualised structurally after culturing cells in folate-deficient media. Unusually, the mutation can be transmitted through a phenotypically normal male. There is already some evidence that the gene loci for G6PD and factor IX are linked to this mental retardation locus. We have followed the inheritance of a DNA sequence 52A, in fragile site families that are also informative for factor IX. We demonstrate that these probes are localised at Xq27/Xq28-Xqter, close physically to the fragile site. We did not find close linkage between 52A, factor IX, and the fragile site in the families studied despite 52A and factor IX showing linkage in normal families. We discuss the importance of these data for the genetic mapping of this region of the human X chromosome and the implication for the use of these DNA probes for clinical diagnosis.
X连锁智力迟钝最常见的形式之一与人类X染色体Xq27处的一个脆性位点有关，在缺乏叶酸的培养基中培养细胞后，该位点在结构上可以显现出来。不同寻常的是，这种突变可以通过表型正常的男性传递。已有一些证据表明，葡萄糖-6-磷酸脱氢酶（G6PD）和凝血因子IX的基因座与这个智力迟钝基因座相连。我们在对凝血因子IX也具有信息性的脆性位点家族中追踪了DNA序列52A的遗传情况。我们证明这些探针定位在Xq27/Xq28-Xqter，在物理位置上靠近脆性位点。尽管在正常家族中52A和凝血因子IX显示出连锁关系，但在我们研究的家族中，我们没有发现52A、凝血因子IX和脆性位点之间存在紧密连锁。我们讨论了这些数据对于人类X染色体该区域基因定位的重要性以及这些DNA探针用于临床诊断的意义。
