A Clinical Trial of Dantrolene Sodium in Pediatric and Adult Patients With Wolfram Syndrome

The Primary Objective of this study is: To assess the safety and tolerability of dantrolene sodium administered orally at upper end of therapeutic dose range for 6 months in patients with Wolfram syndrome with an optional extension phase up to 24 months. Patients who express the wish to continue in the optional extension phase on dantrolene sodium will be offered this possibility. The Secondary Objectives of this study are: * Determine the effect of dantrolene sodium on remaining beta cell functions using a mixed-meal tolerance test and monitoring base-line C-peptide levels, blood glucose levels, proinsulin/C-peptide ratios, hemoglobin A1c levels, and urine glucose levels. * To determine the efficacy of dantrolene sodium on visual acuity (LogMar scores) * To determine the efficacy of dantrolene sodium on visual functions using Visual Functioning Questionnaire - 25. * To evaluate the efficacy of dantrolene sodium on neurological functions using the Wolfram Unified Rating Scale (WURS) and standard neurological assessments.