Interspersed repeat analysis of the MECP2 region. (A) Comparison of several regions on the X chromosome for potential differential enrichment in an interspersed repeat class (Alu, LINE, LTR elements, DNA elements, other repeats). (Random) Random DNA sequence on chromosome X (total length: 1140 kb); (BP-regions) sum of all breakpoint regions (total length of sequence is 113 kb); (Xq28) Xq28 region ranging from 152.5 to 153.6 Mb chopped into 100-kb fragments (total length, 1133 kb); (PLP1) BAC/PAC clones covering 231 kb of the PLP1 region. The Alu repeat content of all breakpoint regions (BP-regions) was significantly enriched compared with other analyzed sequences on the X chromosome. The other classes of interspersed repeats did not show significant differences. (B) GC content of the different genomic regions.