LZTS3 and Intellectual disability: In addition to its role in cancer, LZTS1 was also shown to be important during neuronal development [24]. LZTS1 belongs, together with LZTS2, LZTS3, and N4BP, to the Fezzins, a family of proteins that share a leucine zipper Fez domain [25]. LZTS1 itself was not linked to joint hyperlaxity, but disruption of the ProSAP2 gene, encoding a protein interacting with LZTS2 (LAPSER1), resulted in a syndrome with mild intellectual disability and joint laxity [26, 27].