The remaining six probands (4021, 4482, 4383, 3046, 4353, and 3035) have variants in genes that have not been implicated in CdLS before but are known to be associated with nonsyndromic (NLGN3 [30] and SET [31]) and/or syndromic (EBF3 [32], NR2F1 [33], PUF60 [34], and TBL1XR1 [35, 36]) intellectual disability, respectively (proven de novo in 4482 and 4353). This evidence concerns the gene TBL1XR1 and Cornelia de Lange syndrome.