Karyotypic abnormality of the X chromosome is rare in mutant HPRT-lymphocyte clones.
Lymphocyte clones mutated at the hypoxanthine-guanine phosphoribosyl-transferase (HPRT) locus on the X chromosome were studied by synchronization and G banding to determine the proportion of mutant clones having visible karyotypic change. 47 spontaneously mutant clones, 17 mutant clones induced by X-irradiation and 33 wild-type clones were studied. All clones were karyotypically normal except for 1 clone induced by X-irradiation in which an interstitial deletion of the short arm of the X chromosome had been inserted into the long arm of the same chromosome between q23 and q24; this change may have been coincidental or may have resulted in a position effect mutation. It was concluded that the great majority of mutations were not associated with a visible chromosome abnormality. This conclusion complements molecular studies which suggest that gene changes at the HPRT locus in HPRT- mutants generally extend over segments of DNA too small to be resolved by karyotypic analysis.
Muir
P
P
Department of Haematology, Flinders Medical Centre, Bedford Park, South Australia.
Osborne
Y
Y
Morley
A A
AA
Turner
D R
DR
D002478:Cells, Cultured; D002999:Clone Cells; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000172:deficiency / Q000235:genetics*; D007621:Karyotyping; D008214:Lymphocytes / Q000166:cytology* / Q000528:radiation effects; D009154:Mutation; D012729:Sex Chromosome Aberrations; D014960:X Chromosome
D007041:Hypoxanthine Phosphoribosyltransferase