TBX5 and atrioventricular block: Recently, genome-wide association studies found that the single-nucleotide polymorphism (SNP) rs3825214, located in the T-box 5 (TBX5) gene, was positively associated with the electrocardiography (ECG) PR interval (combined P = 3.3×10−12), duration of the QRS complex (combined P = 3.0×10−13), and QT interval (combined P = 9.5×10−8) and may lead to cardiac arrhythmia such as AF and atrioventricular block (AVB) [7].