A novel RET/PTC variant detected in a pediatric patient with papillary thyroid cancer without ionization history

Papillary thyroid carcinoma (PTC) is the most frequent type of thyroid cancer. Its development is often caused by the formation of RET/PTC fused genes. RET/PTC1 is the most prevalent form, where exon 1 of CCDC6 gene is fused with the intracellular portion of RET protooncogene starting with exon 12. We have discovered a novel RET/PTC1 variant which we have named RET/PTC1ex9 in metastatic PTC of 8-year-old boy. RET/PTC1ex9 detection was performed by real-time polymerase chain reaction with melting curve analysis and subsequent Sanger and next-generation sequencing. A fusion of exon 1 of CCDC6 with exon 9 of extracellular domain of RET followed by exon 12 of RET was revealed. This is the first RET/PTC variant among PTC cases that contain the extracellular part of RET. This observation could be probably explained by incorrect splicing of RET due to the somatic 32-bp deletion in exon-intron 11 boundary of RET.