OCLN and Friedreich ataxia: Cyclooxygenases are increased in several FRDA mouse models and isolated FRDA patient B-lymphocytes, and VEGF is increased in FRDA patient olfactory mucosal mesenchymal stem cells; both pathways are correlated to downregulation of claudin-5 and occludin, the former protein being the essential claudin isoform in brain vasculature (Chen et al., 2009; Chiu and Lai, 2013; Greene et al., 2019; Pérez-Luz et al., 2020; Zhao et al., 2022).