Searching for Tourette’s syndrome gene. Part 2. Patient’s genome variability

Gilles de la Tourette syndrome (GTS) is a complex, heterozygous genetic disorder. Twenty chromosomal rearrangements (7q22-q31, 8q13-q22, and 18q22) indicating genomic regions which may be involved in the etiology of the disorder have been reported in families with GTS. Moreover, pathogenic mutations responsible for GTS were found in the SLITRK1 and the L-histidine decarboxylase (HDC) genes. The W317X mutation in the HDC gene points to a possible role for histaminergic neurotransmission in the mechanism and modulation of tic disorder. The distribution of single nucleotide polymorphisms (SNPs) was examined in at least 14 candidate genes (DRD1, DRD2, DRD3, DRD4, DAT1, MAOA, 5HTR2A, 5HTR3A, TDO2, CNR1, HLA-DRB, IL1RA, MOG, and SGCE) using a case-control genetic association analysis. Still, a lack of replicated and consistent results was observed. Recently, rare structural variants of different genes involved in neurodevelopment determined by recurrent exonic copy number variations (CNVs) have been found in a subset of patients suffering from GTS.