Figure 2.

Assay for allelic methylation status of AR on the X chromosome in female reveals stable clonal maintenance of methylation. Genomic DNA from the same panel of T cell clones used in Fig. 1 was predigested with AluI and HpaII (+) or AluI alone (−), amplified with ARA-specific primers, and separated by PAGE on 10% gels. Two alleles of the polymorphic (CAG)_n are observed in this individual (bands a and b). In peripheral blood (NS1.PHA), both alleles are observed in both HpaII- undigested and -digested, but in T cell clones only one of the two alleles are amplified in HpaII-digested DNA. The methylated allele on the inactive X chromosome is both randomly determined and clonally maintained (23, 24).