Goldstein J L, Marks J F, Gartler S M
Proc Natl Acad Sci U S A. 1971 Jul;68(7):1425-7. doi: 10.1073/pnas.68.7.1425.
Expression of the two X-linked loci glucose-6-phosphate dehydrogenase (G6PD; EC 1.1.1.49) and hypoxanthine:guanine phosphoribosyltransferase (HGPRT; EC 2.4.2.8) was studied in single hair follicles of two females who were heterozygous for both of these genes (double heterozygotes). The coupling phase for these two loci was known to be g6pd A and hyprt(-) on the maternal X chromosome and g6pd B and hgprt(+) on the paternal X. Three phenotypic classes of hair follicles were observed in both double heterozygotes: G6pd A follicles with deficient HGPRT activity, G6pd B follicles with normal HGPRT activity, and G6pd AB follicles with intermediate HGPRT activity. These data directly demonstrate one of the predictions of the Lyon hypothesis that for two X-linked loci, those genes in cis position are turned on or off in a cell and its clone, while in trans only one gene or the other is expressed.
在两名对这两个基因均为杂合子的女性（双重杂合子）的单个毛囊中，研究了两个X连锁基因座——葡萄糖-6-磷酸脱氢酶（G6PD；EC 1.1.1.49）和次黄嘌呤：鸟嘌呤磷酸核糖转移酶（HGPRT；EC 2.4.2.8）的表达情况。已知这两个基因座在母本X染色体上的偶联相为g6pd A和hyprt(-)，在父本X染色体上为g6pd B和hgprt(+)。在这两名双重杂合子中均观察到了三种表型的毛囊：HGPRT活性缺陷的G6pd A毛囊、HGPRT活性正常的G6pd B毛囊以及HGPRT活性中等的G6pd AB毛囊。这些数据直接证明了莱昂假说的一个预测，即对于两个X连锁基因座，处于顺式位置的那些基因在一个细胞及其克隆中被开启或关闭，而处于反式位置时只有一个基因会表达。
