期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1971
卷号：68
期号：7
页码：1425-1427
DOI：10.1073/pnas.68.7.1425
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：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.
