Novel Variants in GABAA Receptor Subunits: A Possible Association with Benzodiazepine Resistance in Patients with Drug-Resistant Epilepsy

Benzodiazepines (BDZ) such as diazepam and lorazepam are popular as first-line treatment for acute seizures due to their rapid action and high efficacy. However, long-term usage of BDZ leads to benzodiazepine resistance, a phenomenon whose underlying mechanisms are still being investigated. One of the hypothesised mechanisms contributing to BDZ resistance is the presence of mutations in benzodiazepine-sensitive receptors. While a few genetic variants have been reported previously, knowledge of relevant pathogenic variants is still scarce. We used Sanger Sequencing to detect variants in the ligand-binding domain of BDZ-sensitive GABAA receptor subunits α1–3 and 5 expressed in resected brain tissues of drug-resistant epilepsy (DRE) patients with a history of BDZ resistance and found two previously unreported predicted pathogenic frameshifting variants – NM_000807.4(GABRA2):c.367_368insG and NM_000810.4(GABRA5):c.410del – significantly enriched in these patients. The findings were further explored in resected DRE brain tissues through cellular electrophysiological experiments.