|Number of repeats||Counts (alleles)||Percentage|
Overview of repeats
Familial adult myoclonic epilepsy type 7 (FAME7) is thought to be caused by expanded TTTCA repeats in the intron 14 of the RAPGEF2 gene as reported by Ishiura et al. (2018) and Lei et al. (2019). The first study was conducted in one family with one member having the identified expansions. The affected individual had 11.1 kb longer allele compared to the normal one, of the unaffected sibling. The expanded allele, in the case of composing only pentanucleotide repeats, would correspond to over 2200 repeats. The configuration of the sequence in the affected individuals is as follows: (TTTTA)exp(TTTCA)exp(TTTTA)exp. None of the 1000 control samples had TTTCA repeats in the locus. Five controls was found to have an expanded stretch of TTTTA repeats, at least in three controls it was in the range of around 60 to 600 repeats (Ishiura et al., 2018). The second published study found just 60 repeats of TTTCA in the RAPGEF2 gene in three affected individuals (Lei et al., 2019).