GLRA1 and hyperekplexia: The isolated hereditary hyperekplexia is caused by defective inhibitory glycinergic neurotransmission and has been associated with genes encoding glycine receptor (GlyR) subunits alpha and beta (GLRA1, GLRB) and solute carrier family 6 member 5 (SLC6A5), of which the variants in glycine receptor alpha 1 (GLRA1) constitute the vast majority (80%) of cases.