Human X-Linked genes regionally mapped utilizing X-autosome translocations and somatic cell hybrids.

Abstract

Human genes coding for hypoxanthine phosphoribosyltransferase (HPRT, EC 2.4.2.8; IMP:pyrophosphate phosphoribosyltransferase), glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49; D-glucose-6-phosphate: NADP+ 1-oxidoreductase), and phosphoglycerate kinase (PGK, EC 2.7.2.3; ATP:3-phospho-D-glycerate 1-phosphotransferase) have been assigned to specific regions on the long arm of the X chromosome by somatic cell genetic techniques. Gene assignment and linear order were determined by employing human somatic cells possessing an X/9 translocation or an X/22 translocation in man-mouse cell hybridization studies. The X/9 translocation involved the majority of the X long arm translocated to chromosome 9 and the X/22 translocation involved the distal half of the X long arm translocated to 22. In each case these rearrangements appeared to be reciprocal. Concordant segregation of X-linked enzymes and segments of the X chromosome generated by the translocations indicated assignment of the PGK gene to a proximal long arm region (q12-q22) and the HPRT and G6PD genes to the distal half (q22-qter) of the X long arm. Further evidence suggests a gene order on the X long arm of centromere-PGK-HPRT-G6PD.Man-rodent somatic cell hybrids have proved important for mapping the human genome (1, 2). Human genes can be assigned to specific chromosomes, since human chromosomes are preferentially lost in these cell hybrids. By employing cells with deleted or translocated human chromosomes in cell hybrid studies, one can determine gene order and assignment to a specific chromosomal region (3-6). The human X chromosome is of interest to map, since it is involved in sex determination; it is functionally inactivated in females, resulting in the same gene dosage as in males (7); and X-linked genes are involved in several inherited metabolic defects.We employed two inherited X-autosome translocations and somatic cell hybrids to map genes coding for hypoxanthine phosphoribosyltransferase (HPRT, EC 2.4.2.8; IMP: pyrophosphate phosphoribosyltransferase), glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49; D-glucose-6-phosphate: NADP+ 1-oxidoreductase), and phosphoglycerate kinase (PGK, EC 2.7.2.3; ATP:3-phospho-D-glycerate 1-phosphotransferase) to specific regions of the X long arm. These three genes have been shown to be X-linked by family and somatic cell genetic studies (3,(8)(9)(10)(11)(12), and enzyme deficiencies of HPRT, G6PD, and PGK in man have been associated, respectively, with Lesch-Nyhan disease (8), drug-induced hemolytic anemia (13), and chronic hemolytic anemia (14).Abbreviations: HPRT, hypoxanthine phosphoribosyl transferase; G6PD, glucose-6-phosphate dehydrogenase; PGK, phosphoglycerate kinase; HAT, hypoxanthine/aminopterin/thymidine; DMEM, Dulbecco's modified Eagle's medium. 2125Mapping the X chromosome in cell hybrids is aided by a system to select for or against hybrid cells possessing human HRPT (15). This procedure, in concert with an X/9 and an X/22 translocation involving different segments of the X long arm translo...

A group of type I keratin genes on human chromosome 17: characterization and expression.

“…2B). Two distinct GK-3- Table 1 were identified by karyotypic analysis and chromosome-specific enzyme markers (59,62). The percent discordant segregation indicates that no chromosome other than human chromosome 17 cosegregated with all of the samples showing GK-3 hybridization.…”

Assignment of the gene for β-glucuronidase (βGUS) to chromosome 7 in man

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“…Gel electrophoresis for identifying the enzyme phenotype was performed as described.1'5 Giemsa-trypsin and Giemsa-9 banding were used to identify the chromosomes as described. 3 groups was observed, eliminating all but chromosomes 3, 4, 7, and 8 as the chromosomes on which fiGUS is located. Chromosome and enzyme studies on 14 man-mouse cell hybrids demonstrated that fiGUS and chromosome 7 segregated concordantly (table I).…”

Confirmation of the assignment of the gene for galactose-1-phosphate uridylyltransferase (E.C. 2.7.7.12) to human chromosome 9

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