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Figure 1. Somatic mutation burden in aging cardiomyocytes. (A) sSNVs increase in human cardiomyocytes and DNA repair pathways become defective with age, particularly the MMR pathway. (B) Polyploidization confers cardiomyocytes tolerance to deleterious effects of mutations compared to diploid cardiomyocytes when mutations affect both alleles. (C) Open questions include the presence of other types of somatic mutations, such as Indels and mutations in mtDNA, and the contributions of sSNVs in the other cardiac cells during the aging process and heart diseases. ROS: Reactive oxygen species; sSNVs: somatic single nucleotide variants; MMR: mismatch repair; NER: nucleotide excision repair; BER: base excision repair; Indels: Insertion-deletion mutations; mtDNA: mitochondrial DNA; 2N: diploid; 4N: tetraploid. The image was created with BioRender.