GPHN and hyperekplexia: In addition to mutations in the genes GLRB (encodes glycine receptor β-subunit), SLC6A5 (encodes glycine transporter 2) and GPHN (encodes the integral membrane protein gephyrin), mutations in the gene GLRA1 (encodes the α1-subunit of the GlyR) account for 40 - 80% of hyperekplexia[6,7].