TBX3 and atrial septal defect: The final set of genes tested are thought to act as (10) markers for a range of developmental, inflammatory and hypertrophic changes ultimately impacting AP generation and propagation, as well as the genes encoding Pgc-1β itself and the complementary Pgc-1α. Translation of both the transcriptional repressor known to affect particular components of the cardiac conduction system, Tbx3 (Sylva et al., 2014), and the major thick filament protein Myh6 (MHC-α) whose mutations are associated with late-onset hypertrophic cardiomyopathy, atrial septal defects and sinus node disorder (Huang, 2017).