In the SNX17-Retriever-CCC-WASH sorting pathway, WASHC4 has been reported as a causative gene for autosomal recessive intellectual disability (MIM615817), and CCDC22 and WASHC5 are known as responsible genes for Ritscher-Schinzel syndrome (RSS, MIM220210 and MIM300963), also known as 3C syndrome due to its triad of clinical features including craniofacial features, cerebellar anomalies and cardiac defects.8–12 We previously reported siblings with biallelic loss-of-function variants in VPS35L, which is listed as the third responsible gene for RSS (MIM619135). This evidence concerns the gene CCDC22 and Ritscher-Schinzel syndrome.