MT-TL1 and atrial fibrillation: MtDNA mutations are strongly associated with cardiovascular disease [7], with specific examples including mtDNA abnormalities in dilated cardiomyopathy [89], increased mtDNA deletions in atrial fibrillation [31], the MTTL1 m.3243A>G mutation and sudden cardiac death [90], and small deletions or heteroplasmic length variants in chronic atrial fibrillation [32].