Figure 4.

(A) Small-pool PCR analysis of repeat length in fibroblast clones that have constitutive expression of (CTG)•(CAG) repeats. Representative lanes of small-pool PCR are shown. The scale on the left shows the molecular weight markers converted into numbers of CTG repeats. Cells were harvested after 32 days of clonal expansion. (B) Histograms of repeat length distributions in clones with constitutive expression of (CTG)•(CAG) repeats. The distribution of unstable alleles is shown by gray bars (left vertical axis). The frequency of the stable allele is shown by black bars (right vertical axis). Fifty alleles from four different clones in a same group were analyzed for each construct. Allele lengths are grouped in bins spanning 50 repeats.