ABNORMALITIES IN T-CELL RECEPTOR LOCUS AND T-CELL LEUKEMIA

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The molecular involvement of T-cell Receptor (TCR) alpha/delta locus at chromosome 14q11.2 in a number of translocations such as t (8 ; 14) (q24 ; q11), t (14 ; 14) (q11 ; q32), inv (14) (q11 ; 32), t (11 ; 14) (q13 ; q11), t (11 ; 14) (p15 ; q11), t(10 ; 14) (q23 ; q11), an t (1 ; 14) (p32 ; q11) has been described in the HTLV-I-begative T-cell malignancies. Those breakpoints specifically occur within the Jdelta, Jalpha or Dalpha region of the TCR alpha/delta locus. However, there is no report which indicates the direct involvement of TCR alpha/delta locus adult T-cell leukemia (ATL) despite the fact of frequent occurrence of translocations at 14q11.2 region. At the first step to characterize the molicular involvement of TCR alpha/delta locus in ATL cases, we isolated 13BAC and 158 cosmid clones which cover more than 1Mb of region spanning entire TCR alpha/delta locus. We found there are 53 Valpha segment and 3 Vdelta segment in the entire TCR alpha/delta locus. Furthemore We localized the deltaRec locus in between Valpha19.1 and Vdelta2.1 and these findings suggest that the rearrngement between deltaRec and pseud Jalpha locus will cause the deltetion of Vdelta2.1-Ddelta-Jdelta-Cdelta-Vdelta3.1 region during the differentation of alpha/beta positive T-cells. By using those BAC clones as probes, we found that the translocation does occur within TCR alpha/delta locus in a case of ATL patient carrying chromosome abnormalities inv(14) (q11q32) and del (14) (q11q32).