DICER1 Mutations in the Era of Expanding Integrative Clinical Sequencing in Pediatric Oncology.

Abstract

<i>DICER1</i> syndrome is a recently described inherited cancer predisposition syndrome caused by pathogenic variants in <i>DICER1</i>. With the recent increase in integrative clinical sequencing for pediatric patients with cancer, our understanding of the <i>DICER1</i> syndrome continues to evolve, as new and rare pathogenic variants are reported. As the frequency of integrative clinical sequencing increases, discussions regarding challenges encountered in the interpretation of sequencing results are essential to continue to advance the field of cancer predisposition. The purpose of this work was to identify patients with somatic and/or germline <i>DICER1</i> variants in our patient population and to discuss sequencing interpretation and the clinical recommendations that result from the integrative clinical sequencing results. Patients were enrolled in the PEDS-MIONCOSEQ study. This integrative clinical sequencing study includes paired tumor/normal whole-exome sequencing and tumor transcriptome sequencing. Patients identified as having <i>DICER1</i> variants were included. We report a <i>DICER1</i> variant of unknown clinical significance in a patient with a highly unusual response to therapy. Two patients had diagnoses clarified once the integrative clinical sequencing revealing a <i>DICER1</i> variant was available. We also discovered a patient with low-level <i>DICER1</i> mosaicism and the challenges encountered in the sequencing interpretation for this patient. In addition to the sequencing data and result interpretation, this work also highlights testing and screening recommendations made to patients with <i>DICER1</i> variants and their families on the basis of these results. This work serves to extend the <i>DICER1</i> phenotype and advance the utility of clinical integrative sequencing in the fields of pediatric oncology and cancer genetic predisposition.