Epilepsy inducing mutation of the GABA-A receptor alpha 1 subunit (360G-Wellcome-202489_Z_16_Z)

We will investigate how a newly discovered mutation to the GABA-A receptor alpha 1 subunit gene (GABRA1) is causing epilepsy in a young child. A single mutation has been identified, which resides in the receptor's first transmembrane domain. This is near the previously identifed neurosteroid binding site from which endogenous neurosteroids can positively modulate GABA-A receptor activity. To investigate the implications of this mutation we have formulated the following aims that will be addressed using heterologous expression of GABA-A receptors in a cell line: 1. To establish the effect of the mutation on GABA concentration response curves and current voltage relationships for typical synaptic and extrasynaptic-type GABA receptors. 2. To determine if known allosteric modulators of GABA-A receptors are affected by the alpha1 subunit mutation. 3. To deduce if the expression levels and receptor mobility at the cell surface are affected by the alpha 1 subunit mutation. To achieve these goals, we will use a combination of patch clamp electrophysiology and single particle imaging techniques. This should establish whether the mutation is causing a gain- or loss-of function, or affects receptor trafficking.