Phenotype Expression Variability in Children with GABRB3 Heterozygous Mutations

GABRB3 gene is a recently identified gene located in 15q12 chromosome and encodes for gamma-aminobutyric acid (GABA) receptor subunit beta-3 protein, which is linked to the GABAA receptor. The gene is believed to share a role in inhibitory GABAergic synapses, GABA iron-gated channel function, and possible cellular response to histamine. The β3 subunit is expressed in cerebral grey matter, thalami, hippocampi, and cerebellum, among other structures. Faulty GABRB3 function is linked to several neurological disorders and clinical syndromes. However, the spectrum of such disorders is not yet well known. We present three case reports highlighting the potentially expanding clinical phenotype and variable expression in children with mutated GABRB3 gene.