Importance of monitoring renal function in Myotonic dystrophy type 1: watch this space

<h3></h3> Myotonic Dystrophy Type 1 (DM1) is the commonest muscular dystrophy in adults. A systematic multi-disciplinary care is required to manage multiple systems affected by DM1. Novel therapeutics targeting various aspects of DM1 related aberrant RNA function are now in various stages of clinical trial pipeline. Renal function assessment is important given the metabolic impairment associated with DM1 and also because of the mode of excretion for several of these novel molecules. We studied over 200 DM1 patients in the North of UK to understand the frequency of renal impairment. Total of 220 DM1 patients (51% male, median age 52 years were analysed). 60% of cases were adult onset DM1. Renal functions were assessed annually in at least 127 patients using urea, creatinine. eGFR was calculated using creatinine. Average (±SD) values of creatinine and urea were 62±15.96 and 4.7±1.5. eGFR &gt;90 was considered normal in 83% of the patients whilst in 17% renal function was impaired. Furthermore in 14% of the patients’ creatinine was below 45 probably reflecting a low muscle mass in them. In conclusion, whilst our study identifies that renal function is normal in a majority of the DM1 patients, a notable proportion this is impaired. Cystatin C level that is not reliant on muscle mass may be a sensitive measure of renal function in DM1. Monitoring renal function in DM1 patients is important clinically and for trial preparedness.