Microsatellite repeats often vary across individuals due to which they have been used historically as genetic markers. Some times these repeats can undergo expansions and this can result in genetic abnormalities. The extreme examples of such abnormalities include a group of neurogenetic diseases referred to as Triplet Expansion diseases, examples for which include: Huntington disease, Friedreich's ataxia and Fragile X syndrome. For a long time, such diseases are known only in humans and not in other systems. As a result, there has not been any genetic models to study fundamental aspects of these diseases. Genetic engineering of models have been partly successful. Repeat expansions in coding regions, which result typically in polyglutamine stretches has been easier to engineer as the expansions are relatively small. However, repeat expansions in non-coding regions such as those in Friedreich's ataxia and Fragile X syndrome have been difficult to engineer. Several years ago, we identified populations of Arabidopsis to be displaying a temperature-sensitive growth defect, which was mapped to an intronic repeat expansion (Sureshkumar et al, Science, 2009). This model presents exciting opportunities to uncover mechanisms and my group has been exploiting this to address genetics of repeat expansions (Eimer et al, Cell, 2018; Tabib et al, Front. Plan Sci, 2016). I will present how and why Arabidopsis system can be an effective model to study genetic of triplet repeat expansions.