Number of regions of interest that overlap significant hotspots of W→S mutations. Hotspots were evaluated in the context of genomic regions of different sizes, as indicated (e.g. 5 kb corresponds to a genomic region encompassing 2.5 kb upstream and 2.5 kb downstream of the HAR midpoint). FDR5 indicates the number of hotspots that pass the significance threshold of 5% false discovery rate; “Overall” indicate the total number of significant hotspots regardless of the size of the genomic region considered around HARs (i.e. union of those subsets); numbers in parentheses include HARs that overlap significant hotspots of W→S mutations if the masking effect of stronger hotspots was considered for second and third ranking hotspots.