Is Rett syndrome a chromosome breakage syndrome?

Lymphocytes from venous blood from 15 girls with Rett syndrome (RTS), 7 girls with RTS "forme fruste," and 46 unrelated control females were examined. All subjects had a normal karyotype using RHG and RTBG technique. The frequency of gaps and breaks was determined for each group. A significantly higher (P < 0.01) frequency of chromosome breakage was observed in RTS subjects compared to controls. This work suggests that an increased tendency to chromosome breakage may be part of a genetically determined disorder in RTS patients.