DAP and frontotemporal dementia: For example, the tetranucleotide (CCTG•CAGG) repeat, which contributes to the genetic instability associated with myotonic dystrophy type 2, also folds into a hairpin-like structure [18]; the hexanucleotide repeat (GGGGCC), expansion of which triggers amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), adopts a G-quadruplex (G4) structure [19]; and the hexanucleotide (CCCCCG) repeat found within the promoter of the human DAP gene forms i-motifs under physiological conditions [20].