Figure 1. Imprinting analysis of 15q11-13 GABAA receptor genes.
A) Sequencing chromatograms demonstrate equal biallelic expression of GABRB3 (SNP rs20318) and GABRG3 in control samples. Sequences in upper panels are genomic DNA and sequences in lower panels are from cDNA. Black arrows highlight the SNP in each chromatogram. AUT 797 shows clear monoallelic expression of GABRB3 and GABRG3 and RTT 5214 has skewed expression of the T allele in GABRG3. Both forward and reverse directions were sequenced for each individual and the chromatograms were consistent. B) Allele-specific restriction digestion analysis of GABRA5 demonstrates normal equal biallelic expression in controls and most autism and RTT samples. The upper panel contains AccI digested genomic DNA from each individual and the lower panel contains AccI digested cDNA products. AccI cuts the C allele but does not cut the T allele of the GABRA5 SNP. Controls and several autism and RTT samples demonstrate equal biallelic expression, however only the C allele of GABRA5 was detected in AUT 5173.