Here, we report five patients with WS with 1.4 Mb–1.5 Mb microdeletions that include RFC2, as well as one patient with a 167-kb microdeletion involving RFC2 and six patients with intragenic variants within RFC2. To investigate the potential involvement of RFC2 in WS pathogenicity, we generate a rfc2 knockout (KO) zebrafish using CRISPR-Cas9 technology. Here, RFC2 is linked to Werner syndrome.