The genetics of atrial fibrillation

As mentioned in the epidemiology section, atrial fibrillation (AF) incidence is lower in African Americans, Hispanics and people of Asian descent compared with Caucasians, which may suggest a genetic component.6 Further evidence supporting a genetic component emerged in studies from a variety of populations showing that having a parent with AF markedly increases the likelihood of developing the arrhythmia. In one study, the likelihood of developing AF was 1.85 in people with one parent who had the arrhythmia compared with controls. The risk increased to 3.23 in those whose parent developed AF when older than 75 years of age.26

Family studies and genotyping of sporadic cases identified numerous rare genetic variants that seem to contribute to AF.25 Moreover, genome-wide association studies link more than 30 common genetic variants with AF, many of which encode loss-of-function or gain-of-function channelopathies (defects in ion channels caused by genetic or acquired factors, such as toxins or drugs).25,27 Other polymorphisms linked to AF are associated with transcription factors (proteins that regulate gene activity by increasing or reducing binding of RNA polymerases to DNA) associated with cardiac genes.25 Future investigations of transcription factors might elucidate how developmental abnormalities affecting the heart may predispose to AF in later life.25

Other polymorphisms associated with AF encode:25

  • structural components in the myocardium, such as the light and heavy chains of the contractile protein myosin
  • structural components in gap junctions, which allow a depolarising current to travel between myocytes and help synchronise cardiac contraction
  • encode proteins involved in signalling or protein turnover.

 

Review the genetic interactions between atrial fibrillation and stroke


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