New GABA_A receptor alpha5 subunit gene polymorphism that may confound genotyping

We report the discovery of a new GABA_A receptor alpha5 subunit gene polymorphism close to the polymorphism described by Glatt et al. (GT) ₅GCGTGC(GT)₂₁. This new polymorphism is of great importance, because it means that non-denaturing acrylamide gels used to separate the different alleles of the polymorphism described by Glatt et al. cannot distinguish an allele with the sequence: (GT)₄GCGTGC(GT)n from another allele with the sequence: (GT)₄(GCGT)₄GC(GT) _n-6. These gel fragments are separated by size, which would be the same in these two cases. An alternative would be to use an analysis method that can detect base changes, for instance, single strand conformation polymorphism (SSCP) or denaturing gradient gel electrophoresis (DGGE).