Pentanucleotide repeat-related disorders: Genetics and bioinformatic discovery and detection

In recent years, a large group of familial epilepsies and hereditary ataxias have emerged, caused by an extraordinary type of a novel pentanucleotide repeat expansion that has arisen in a preexisting nonpathogenic repeat tract. Remarkably, these insertions have occurred in noncoding regions of genes expressed in the cerebellum, but with highly diverse functions. These conditions, clinically very heterogeneous, may remain underdiagnosed in patients with atypical phenotypes and age at onset. They share, however, many genetic and phenotypic features, and discovery or detection of their pathogenic pentanucleotide repeats for diagnostic purposes can be achieved using recent bioinformatic methods. Here, we focus on the latest advances regarding the peculiar group of pentanucleotide repeat-related disorders beyond epilepsies.