NKX2-5 and atrial fibrillation: Numerous studies now indicate that polymorphisms in genes encoding the cardiac transcription factors NKX2-5 and PITX2C increase susceptibility to atrial fibrillation (Huang et al. 2013; Qiu et al. 2014; Wang et al. 2014; Xie et al. 2013), suggesting the potential involvement of disrupted gene networks in this disorder.