Fragile X full mutations are more similar in siblings than in unrelated patients: further evidence for a familial factor in CGG repeat dynamics

Abstract

Purpose: We sought to compare patterns of full mutation repeat-length variability in the peripheral blood DNA of patients with fragile X syndrome to determine whether siblings possess mutation patterns more similar than those of unrelated patients.

Methods: Mutation patterns were visualized by Southern blot analysis and captured digitally with a phosphor imager. Novel comparison strategies based on overlapping profile plots and calculation of weighted mean CGG repeat values were used to assess mutation pattern similarity.

Results: Within the population that we analyzed of 56 patients with full mutation, mutation patterns were found to be more similar in siblings than in unrelated patients.

Conclusion: These results indicate that repeat-length variability may be generated in a nonrandom manner and that familial factors influence this process.