Family C consisted of 5 affected individuals over 4 generations. Four patients (C/II-1, C/III-1, C/IV-1, and C/IV-2) had simple FS with an age at onset between 10 and 14 months. No information was available on the epilepsy type of the deceased patient (C/I-1) of the first generation. FS spontaneously remitted before age 3 years, except in individual C/IV-1, whose FS lasted up to age 8 years, therefore designated as FS+. None of the patients had subsequent epilepsy. Sequencing of the index case (C/III-1) revealed a heterozygous single base deletion (c.1382delG) in exon 9 of GABRG2, also present in his affected sons, but not in his father (C/II-1), which is another example of phenocopy. DNA of his mother was not available for genetic studies to investigate the mode of transmission of the mutation. This variant creates a frameshift, resulting in loss of the last 6 C-terminal amino acids and incorporation of 32 extra amino acids with a final predicted peptide of 493 amino acids instead of 467 (p.Val462fs*33).
