Schematic depiction of terms used in the literature and this manuscript for different classes of tandem repeats. N = nucleotide in tandem repeat motif, lower case number indicates the number of nucleotides in any given tandem repeat motif. Red box indicates the tandem repeat motif classes studied in this work. The referenced studies are in order of the tandem repeat motif length listed in the schematic:  Nature Genetics, Ishiura et al., 2018.  Molecular Neurodegeneration, Ebbert et al., 2018.  bioRxiv preprint, de Roek et al., 2018.  Nature Biotechnology, Jain, Olsen et al. 2018.