NRG1 and hypoparathyroidism-retardation-dysmorphism syndrome: Targeted therapy is an option for a small percentage (4 to 7%) of PDAC patients with specific genetic variants (BRCA1/2, PALB2, homologous recombination deficiency (HRD), BRAF V600E, Neurotrophic tyrosine receptor kinase (NTRK) mutation, and rearranged during transfection (RET) and neuregulin 1 (NRG1) gene fusion-positive tumors), as recommended by The National Comprehensive Cancer Network (NCCN) guideline [2].