A de novo missense variant in GABRA4 alters receptor function in an epileptic and neurodevelopmental phenotype

Abstract

Variants in γ-aminobutyric acid A (GABA_A ) receptor genes cause different forms of epilepsy and neurodevelopmental disorders. To date, GABRA4, encoding the α4-subunit, has not been associated with a monogenic condition. However, preclinical evidence points toward seizure susceptibility. Here, we report a de novo missense variant in GABRA4 (c.899C>T, p.Thr300Ile) in an individual with early-onset drug-resistant epilepsy and neurodevelopmental abnormalities. An electrophysiological characterization of the variant, which is located in the pore-forming domain, shows accelerated desensitization and a lack of seizure-protective neurosteroid function. In conclusion, our findings strongly suggest an association between de novo variation in GABRA4 and a neurodevelopmental disorder with epilepsy.

Keywords: Drug-resistant epilepsy; GABAA receptors; early-onset epilepsy; neurosteroid; tonic inhibition; trio exome sequencing.