Sequencing of exon 1a promoter region and exon 8 of GABRB3 gene for identification of SNPs in Iraqi autistic patients.

The γ-aminobutyric acid receptor β3 subunit (GABRB3) gene is located on chromosome 15q12 and it has been implicated in the neurobiology of ASDs. The aim of this study was to correlate between GABRB3 and ASDs. This study included 40 autistic patients and 25 non-autistic controls (5 unaffected sibling and 20 healthynon-relatives). Genomic DNA was extracted from blood samples followed by PCR amplification of exon 1a promoter region and exon 8 of GABRB3 for subsequent DNA sequencing using Sanger method. Identical bands related to the targeted regions were present in all samples. Samples of patients with similarities in autistic phenotypes were sent for direct sequencing by Macrogen Company, South Korea, along with control samples. BLAST results revealed that promoter region contained 16 SNPs (8 only in autistic patients, 2 only in controls, and 6 found in both). Three of them were common SNPs (rs7171660, rs4363842 and rs4906901) and were present in all (autistic and control samples) while the remaining promoter SNPs (13 SNP) are reported for the first time in this study. Exon 8 showed 100 % sequence identity in all samples as it had no SNPs, while the sequenced part of the following intron 8 appeared to have a SNP (rs3751582) in 3 autistic patients and 2 controls. SNPs found only in autistic patients are likely associated with ASDs and promoter SNPs could alter expression of the gene thus contributing to the pathogenicity of autism.