Multiple methylation-free islands flank a small breakpoint cluster region on 11p13 in the t(11;14)(p13;q11) translocation.

The t(11;14)(p13;q11) translocation is one of the most frequent chromosomal abnormalities in T-cell acute lymphoblastic leukemia (ALL). Ten different leukemias carrying this translocation have been analysed and all 10 breakpoints fall within a region of less than 25 kb on chromosome band 11p13. We have used PFGE and cosmid cloning to assess the presence of potential genes by analysing methylation-free islands in the vicinity. Four methylation-free islands, within 270 kb, flank the t(11;14)-associated breakpoint cluster region (T-ALLbcr), one occurring about 25 kb on the telomeric side and one about 100 kb on the centromeric side of the T-ALLbcr. Evidence for eight further methylation-free islands on both sides of the T-ALLbcr region is also presented. Thus multiple methylation-free islands exist on 11p13 flanking the t(11;14)(p13;q11) translocation-associated breakpoint cluster region, representing multiple potential transcription units whose chromosomal environment is altered by chromosome translocation.