Several different potentially deleterious mutations in genes of the lectin arm of the complement system - such as MASP1, COLEC10, and COLEC11 genes – have been described in patients with 3MC syndrome (Sirmaci et al., 2010; Rooryck et al., 2011; Atik et al., 2015; Urquhart et al., 2016; Gardner et al., 2017; Munye et al., 2017; Graul-Neumann et al., 2018; Basdemirci et al., 2019). The gene discussed is COLEC11; the disease is 3MC syndrome.