Missense mutations and subsequent downregulation of CCDC22 are potential mechanisms underlying X-linked intellectual disability (Voineagu et al., 2012; Kolanczyk et al., 2015) and Ritscher-Schinzel syndrome (Kolanczyk et al., 2015; Neri et al., 2022; Gjerulfsen et al., 2021) in humans. This evidence concerns the gene CCDC22 and Ritscher-Schinzel syndrome.