Cloning and molecular characterization of part of a new gene fused to HMGIC in mesenchymal tumors.

Aberrations of the HMGIC gene, encoding an architectural transcription factor and located in the chromosomal region 12q15, are very frequent among benign mesenchymal tumors, such as lipomas, uterine leiomyomas, or pulmonary chondroid hamartomas. These HMGIC aberrations are caused by characteristic structural chromosomal aberrations, either visible by conventional cytogenetics or as cryptic abnormalities. Some of these aberrations of chromosome 12 are not specific for particular tumor entities but can occur in a variety of tumors with HMGIC abnormalities. One such example is the pericentric inversion inv(12)(p11.2q15). Starting from the ectopic sequence derived from an HMGIC fusion transcript of an aggressive angiomyxoma with such an inversion we established three PAC clones covering the breakpoint region 12p11 and cloned part of a yet unknown gene in 12p11.2, which is fused to the third exon of HMGIC. Using fluorescence in situ hybridization with these PACs we were able to show that the same region was involved by 12p11.2 aberrations in lipomas, aggressive angiomyxomas, and pulmonary chondroid hamartomas.