CHRNA gene alterations in epilepsy: A systematic review of alpha subunit associations with ADSHE, SeLIE, and SeLECTS

BACKGROUND AND OBJECTIVES: Epilepsy is a complex disorder with multiple provoking factors and etiologies. Certain genetic alterations in certain genes have been related to the development of various types of epilepsy. We performed a systematic review to evaluate associations between four nAChR alpha subunit genes (CHRNA2/3/5/6) and epilepsy subtypes. METHODS: We searched PubMed, Scopus, Academic Search Ultimate, CINAHL, and MEDLINE Complete (October 2024) for studies linking CHRNA2/3/5/6 mutations to epilepsy. CHRNA4 was excluded because it was recently comprehensively analyzed in a meta-analysis. This study included all original peer-reviewed evidence discussing the association between any nicotinic alpha subunit of cholinergic receptor genes and any epilepsy. There were no date limitations, but studies investigating non-human subjects or written in languages other than English with no translation were excluded, along with any study discussing the mentioned genes or epilepsies without a correlation identification or discussion. This review uses the current ILAE 2022 nomenclature. RESULTS: A total of 193 records were identified, of which 39 records have been sought for retrieval, and 21 studies were eventually included in the final review. Thirteen studies discussed CHRNA2, and four studies discussed both CHRNA3 and CHRNA5, while each of these two genes was being discussed alone by only one study, and two studies discussed all four genes, including CHRNA6. Among the four genes examined in this research, CHRNA2 showed the highest frequency of association with pathogenic mutations. CONCLUSION: While many epilepsy patients were found to have no mutation in the four CHRNA genes investigated, some genetic studies showed mutations in CHRNA2 related to ADSHE, while others showed no association, with a possibility of CHRNA5 being related to self-limited epilepsy with centrotemporal spikes (SeLECTS).