The importance of NRXN1 in mediating cell-cell interactions in the central nervous system, as well as its confirmed involvement in other neurodevelopmental disorders, make this gene an excellent candidate gene for TS [12], [29], [30]. Our results are consistent with those of a previous study reporting deletions affecting NRXN1 exons 1–3 in TS, the same exons found to be deleted in our study [12]. The fact that two of the three NRXN1 rearrangements, for which inheritance status could be confirmed, were found to be de novo events, is in line with recent findings stressing a role for de novo mutations in neurodevelopmental disease. The potential involvement of COL8A1 in TS is intriguing. A growing body of evidence suggests that collagen subunits are involved in neural development, influencing processes such as axonal guidance, synaptogenesis and Schwann cell differentiation [31], [32]. COL8A1 has also been found to be up-regulated during repair processes in the mouse brain [32]. Interestingly, the top signal in the recent GWAS of TS [8] also implicated a collagen gene (COL27A1).
