Mapping of the 8q 12 translocation breakpoint to a 40-kb region in a pleomorphic adenoma with an ins(8;3)(q12;p21.3p14.1)

The translocation t(3;8)(p21;q12) is the most common chromosome abnormality observed in pleomorphic adenomas of the salivary glands. In this paper we describe the physical mapping of the breakpoints in an adenoma with a variant t(3;8), viz., an ins(8;3)(q12;p21.3p14.1). Using sequence-tagged sites (STSs) corresponding to landmarks within a previously identified yeast artificial chromosome (YAC) spanning the breakpoint in adenomas with t(3;8), cosmids isolated from a chromosome 8-specific cosmid library. The 8q12 insertion breakpoint was mapped by FISH to a 300-kb region flanked by MOS and a new STS, CH129. A cosmid within this region was shown to span the breakpoint. To test whether the recently identified FHIT gene, which maps to 3p14.2, was disrupted by the 3p rearrangement, we also isolated an FHIT YAC and mapped this YAC by FISH distal to the most proximal 3p breakpoint. In addition, RT-PCR analysis revealed only a normal-sized FHIT transcript, suggesting that FHIT is not affected by the 3;8-rearrangement.