An Exploration of Vitamin D Deficiency and Clinical Status in Friedreich's Ataxia Patients in the UK

Vitamin D deficiency has been described in several neurodegenerative conditions. Friedreich's ataxia (FRDA) is the most common inherited neurodegenerative ataxia, characterized by progressive gait, limb and trunk ataxia, together with peripheral neuropathy, pes cavus, skeletal deformities, and cardiomyopathy. The result is a highly disabling disease in which early falls are common, and wheelchair use is common by the third decade.1 There is a lack of evidence looking at bone health in FRDA and so the aim of the current study was to review the vitamin D status in a large cohort of FRDA patients, and explore the potential causes and consequences of vitamin D deficiency in this population. This was a retrospective analysis using records from the London arm of the European Friedreich's Ataxia Consortium of Translational Studies (EFACTS) database. Eighty-two genetically confirmed FRDA patients with at least one serum 25-hydroxy vitamin D (25-OHD) measurement were identified, of which 26 were excluded due to current vitamin D supplementation. Demographic and clinical data, including disease duration, SARA (Scale for the Assessment and Rating of Ataxia) scores, and presence of falls, were collected. Because this was a service evaluation project, informed consent was not required. Basic descriptive and clinical data can be found in Table 1. Fifty-six patients were enrolled in the study (23 males). The median 25-OHD level was 31.8 nmol/L (23.1–49.9, interquartile range) and did not differ significantly between male and female patients. Falls were experienced by 81.1% of patients and in terms of mobility, 55.4% of patients were wheelchair-bound, 17.9% were ambulatory but used a wheelchair regularly, and 26.8% of patients were fully ambulatory. There were no associations between 25-OHD levels and SARA score, disease duration, age at onset, age, falls, the presence of lower limb proximal muscle weakness or its severity, or ambulatory status. In this study we confirmed that vitamin D deficiency is prevalent in FRDA patients. In line with the UK National Institute for Health and Care Excellence definition we used thresholds of