Like mitochondrial myopathy, Seckel syndrome is genetically heterogeneous and disease mutations affect groups of genes with roles in DNA replication/repair (ATR, DNA2, CTIP, NSMCE2, and TRAIP) and segregation of the replicated genome into daughter cells (CEP63, CEP152, CENPJ, NIN, and NSMCE2). This evidence concerns the gene DNA2 and Mitochondrial myopathy.