A Multifocal Pediatric Papillary Thyroid Carcinoma (PTC) Harboring the <i>AGK-BRAF</i> and <i>RET/PTC3</i> Fusion in a Mutually Exclusive Pattern Reveals Distinct Levels of Genomic Instability and Nuclear Organization. The gene discussed is RET; the disease is thyroid gland papillary carcinoma.