Joyce Axelman

TL;DR: Testing two heterozygotes for X-linked STS deficiency who were also heterozygous for the common electrophoretic variants of glucose-6-phosphate dehydrogenase provides evidence, presented here, for differential expression of STS loci on the active and inactive X chromosome.

TL;DR: It is found that heterozygotes who are more than 10 yr old have an excess of HPRT+ skin fibroblast clones but this excess does not increase with age, and age-related reactivation is not a feature of all X-linked loci, and may have species, tissue and locus-specific determinants.

TL;DR: F fused Tay-Sachs with Sandhoff fibroblasts and obtained cultures containing heterokaryons which produce a hexosaminidase which is absent from the parent lines, which has the electrophoretic and heat lability characteristics of the Hex A found in normal fibro Blasts.

TL;DR: Studies of a unique clone of skin fibroblasts from a normal 46 XX female reveal that the G6PD locus on the inactive X chromosome has been derepressed, and observations of the glucose-6-phosphate dehydrogenase phenotype in these heterozygous cells indicate that the reactivated X produces only half the enzyme subunits as are produced by the active X.

TL;DR: It is reported that when cell cultures are established from these tissues, the silent G6PD locus is depressed, and observations suggest that without DNA methylation to maintain the silence of the locus, tissue or cell-specific factors act to repress the silent locus but are unable to maintain inactivity through cell division, or are lost as cells proliferate in culture.