OXTR and generalized anxiety disorder: This study therefore employed a multidisciplinary approach to concurrently investigate: (1) baseline serum OT levels between GAD patients and healthy controls (HCs), with consideration of sex differences; (2) the association between OXTR rs2254298 genotype and escitalopram treatment response; and (3) the interrelationships between OT levels, genotype, clinical severity, and treatment outcome.