Molecular analysis of a t(7;14)(g35;g32) chromosome translocation in a T cell leukemia of a patient with ataxia telangiectasia

Molecular analysis of somatic cell hybrids derived from T cells carrying a t(7;14)(g35;g32) chromosomal translocation from a patient with ataxia telangiectasia and T cell leukemia indicates that the breakpoint on chromosome 14 is proximal to the IgH locus and to the D14S1 locus, while the breakpoint on chromosome 7 involves the T cell receptor β chain locus immediately 5′to Jβ 1.5 on chromosome 7. The separation of Vβ and Cβ observed in somatic cell hybrids defined the orientation of the T cell receptor β chain locus on chromosome 7 where the Vβ genes are centromeric and the Cβ genes are telomeric. A novel chromosomal alteration, undetected cytogenetically, was revealed as being an inversion with duplication of the distal band of chromosome 14832. The importance of the 14832 region in the leukemogenic process is discussed.