Benchmarking ZFN-Site against a published CCR5 ZFN off-target analysis. Previously, Perez et al. used SELEX to determine the relaxed specificity of a ZFN pair targeting the CCR5 gene and used this data to scan the genome. We scanned the human genome with ZFN-Site, configured as shown, using the CCR5 ZFN half-sites from Perez et al. with ambiguities matching their SELEX data. The bases allowing substitutions are shown in lower case letters. ZFN-Site found each site they listed, paired with their results in Figure 4.