Regional mapping of the human immunoglobulin lambda light chain to the Philadelphia chromosome in chronic myeloid leukaemia.

The lambda light chain immunoglobulin constant region (C lambda) locus was mapped on human chromosome 22. A DNA probe containing part of the C lambda locus was isolated from a human chromosome 22 genomic library, and a series of rodent X human somatic cell hybrids (each of which contained different translocated parts of chromosome 22) were constructed and characterized. The hybridization of the C lambda probe to DNA from these cell hybrids was then studied by Southern blot analysis. The results demonstrates that the C lambda locus is situated very close to the translocation breakpoint on human chromosome 22 which is characteristic of chronic myeloid leukaemia, and at least part if not at all of the locus is situated on the Philadelphia chromosome.