CTC1 and Coats plus syndrome: This clinically and genetically highly heterogeneous group of syndromes includes mitochondrial diseases (predominantly mtDNA mutations), Aicardi–Goutières syndrome (ADAR, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, TREX1, IFIH1), Coats plus syndrome (CTC1), leukoencephalopathy with calcifications and cysts (SNORD118), Cockayne syndrome (DDB2, ERCC1, ERCC2, ERCC3, ERCC4, ERCC5, ERCC6, ERCC8, GTF2H5, MPLKIP, POLH, XPA, XPC) and many others.