Expression of Two X-Linked Genes in Human Hair Follicles of Double Heterozygotes

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 68; no. 7; pp. 1425 - 1427
• Main Authors: Goldstein, Joseph L., Marks, James F., Gartler, Stanley M.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01.07.1971; National Acad Sciences
• Subjects: Adenine - metabolism; Adenine Nucleotides; Adolescent; Adult; Alleles; Biological Sciences: Genetics; Carbon Isotopes; Child; Electrophoresis; Female; Follicles; Genes; Genetic loci; Genetics, Medical; Glucosephosphate Dehydrogenase - analysis; Guanine Nucleotides; Hair - enzymology; Hair follicles; Heterozygote; Heterozygotes; Humans; Hypoxanthines; Isoenzymes - analysis; Lesch-Nyhan Syndrome - enzymology; Male; Middle Aged; Mutation; Pentosephosphates; Phenotypes; Radioisotopes; Sex Chromosomes; Transferases - analysis; Tritium; X Chromosome inactivation; X linked genes
• ISSN: 0027-8424; 1091-6490
• 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 hgprt-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.