Although hypermobile Ehlers-Danlos syndrome (hEDS) is the most common type of EDS, its genetic etiology is unclear. This study presents 5 cases who had both a hEDS phenotype and FMR1 premutation. In premutation carriers, a possible connection between both conditions could be explained by a depletion of fragile X mental retardation protein (FMRP), a major regulatory protein for extracellular matrix (ECM) function. An increase of FMR1 mRNA could be another possible link between the two conditions, as it could lead to RNA toxicity, mitochondrial dysfunction, and eventually tissue inflammation. Clinicians should recognize the occurrence of both conditions and consider testing for the premutation when evaluating those diagnosed who present with a hEDS phenotype. (By Dr. Nattaporn Tassanakijpanich, https://jmg.bmj.com/content/early/2021/06/29/jmedgenet-2020-107609 )