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Novel FRMD6::PTH chimera in tumorous bone lesion carrying a t(4;11;14;12)(q35;p15;q22;q13)
Ioannis Panagopoulos1,2, Kristin Andersen1, Isabel Lloret3
1Section for Cancer Cytogenetics, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway.
Background:
Benign fibro-osseous lesions are characterized by the replacement of normal bone with cellular fibrous connective tissue with new bone formation. The published cytogenetic information on these tumors is limited to only few cases. Here, we report the cytogenetic and molecular genetic findings of a fibro-osseous tumor.
Methods:
A fibro-osseous lesion was investigated for genetic abnormalities using banding cytogenetics, fluorescence in situ hybridization (FISH), RNA sequencing, and direct cycle Sanger sequencing.
Results:
The karyotype was 46,XX,t(4;11;14;12)(q35;p15;q22;q13)[7]/46,XX [3], with no rearrangement of HMGA2. RNA sequencing revealed two FRMD6::PTH chimeric transcripts, originating from the fusion point 14q22;11p15 of the t(4;11;14;12). In these transcripts, exon 1 of FRMD6 fused to either exon 1 or exon 2 of PTH. Direct cycle sequencing confirmed the presence of these FRMD6::PTH chimeric transcripts.
Conclusion:
This study reports, for the first time, the presence of the FRMD6::PTH chimera in fibro-osseous tumor. In this chimera the expression of the entire coding region of PTH is regulated by the ubiquitously expressed FRMD6 gene promoter. Dysregulation of PTH expression may have significant implications for processes regulated by PTH protein.
