GJA1 and obesity due to melanocortin 4 receptor deficiency: In a trial to explore the relationship between obesity and/or inflammation and induction, progression and recurrence of AF, Zhang et al. [44] found activation of the integrated stress response (ISR) pathway in the left atrium plays a key role in AF induction through activation of ISR pathway-related cardiac fibrosis, inflammatory macrophage infiltration, autophagy, and expression of ion channel and Cx43.