| Abstract | Neuroleptic-induced tardive dyskinesia (TD) is an involuntary movement disorder that develops in patients who have undergone long-term treatment with antipsychotic medications, and its etiology is unclear. In this study, a genome-wide association screening was done to identify the pathway(s) in which genetic variations influence susceptibility to neuroleptic-induced TD.
Screening with Sentrix Human-1 Genotyping BeadChip (Illumina, San Diego, California, USA) was done for 50 Japanese schizophrenia patients with treatment-resistant TD and 50 Japanese schizophrenia patients without TD. A total of 40 573 single nucleotide polymorphisms that were not in linkage disequilibrium with each other and were located in the exonic and intronic regions of 13 307 genes were analyzed. After gene-based corrections, P values for allelic associations were subjected to canonical pathway-based analyses with Ingenuity Pathway Analysis software (Ingenuity Systems, Inc., Redwood City, California, USA).
Eight genes (ABAT, ALDH9A1, GABRA3, GABRA4, GABRB2, GABRAG3, GPHN, and SLC6A11) contained polymorphisms with gene-based corrected allelic P values of less than 0.05. They were aggregated significantly in 33 genes belonging to the gamma-aminobutyric acid (GABA) receptor signaling pathway (P=0.00007, corrected P=0.01). Associations were replicated in an independent sample of 36 patients with TD and 136 patients without TD for polymorphisms in SLC6A11 (GABA transporter 3) (P=0.0004 in the total sample), GABRB2 (beta-2 subunit of GABA-A receptor) (P=0.00007 in the total sample), and GABRG3 (gamma-3 subunit of GABA-A receptor) (P=0.0006 in the total sample).
The results suggest that the GABA receptor signaling pathway may be involved in genetic susceptibility to treatment-resistant TD, at least in a subgroup of Japanese patients with schizophrenia. The present results suggest that benzodiazepines may be considered as possible treatment option for TD. |
| Abstract | A large-scale sequencing screen of X-linked synaptic genes in individuals with autism spectrum disorder (ASD) or schizophrenia (SCZ), two common neurodevelopmental disorders, identified many variants most of which have no easily predictable effect on gene function. In this report, we evaluated the impact of these rare missense and silent variants on gene splicing. For this purpose, we used complementary in silico analyses, in vitro minigene-based assays and RNA prepared from lymphoblastoid cells derived from patients with these mutations. Our goal was to identify the variants which might either create or disrupt an acceptor splice site, a donor splice site or an exonic splicing enhancer, thus leading to aberrant splicing that could be involved in the pathogenesis of ASD or SCZ. We identified truncating mutations in distinct X-linked gamma-aminobutyric acid A (GABAA) receptor subunit-encoding genes, GABRQ and GABRA3, in two different families. Furthermore, missense and silent variants in nuclear RNA export factor 5 and histone deacetylase 6 were shown to partially disrupt the protein. While genes from the GABAergic pathway have previously been thought to be involved in the pathophysiology of ASD, this is the first report of ASD patients with truncating mutations in GABA receptors genes. |
