P.357 - The EUROMAC registry for rare glycogen storage diseases: preliminary report

Abstract

EUROMAC was established to collect comprehensive data on GSDV and related glycogen storage diseases, with the goal to facilitate the characterization of the natural history of rare muscle glycogenoses, report on estimated prevalence and regional differences in phenotype/genotype, assist in the selection of suitable outcome measures, create a comprehensive cohort of patients with rare muscle glycogenoses, from which potentially participants in clinical trials can be recruited, and assist in developing standards of care for muscle glycogenoses. 256 patients were recruited (Denmark n = 10, France n = 23, Germany n = 21, Greece n = 3, Italy n = 34, the Netherlands n = 24, Spain n = 65, the UK n = 70; Turkey n = 6). Diagnosed diseases included GSDV (n = 244), GSD IIIa (n = 2), GSDVII (n = 5), GSDIX (n = 2), GSDX (n = 1), GSDXIV (n = 1), and GSDXV (n = 1). Average age was 66 years (range; 12–87); average age at diagnosis was 31 years. Most diagnoses were based on a molecular genetic confirmatory test (n = 228). Average BMI was 26.1. GSDV population (n = 244): R50X is a hotspot mutation in GSDV and 144 of 244 carried this mutation either as homozygous or compound heterozygous, with a clearly higher incidence in northern European countries in the registry. The average CK level was 2,643 IU/L, but 18 patients had normal CK levels. 29 were reported to have wasting, and interestingly, in several the wasting was preferentially in muscles around the hip. New information has emerged for BMI, CK levels and muscle weakness. Increased BMI may reflect low physical activity levels in the reported sample. CK is not always increased in this population. Muscle weakness in GSDV was reported at a lower frequency than investigations in smaller cohorts that were aimed specifically at studying this. This is probably not surprising as fixed weakness easily can go unnoticed unless specifically tested for. Unfortunately, considerable diagnostic delay was evident, which highlights the need for better awareness of these diseases. The authors would like to thank the study coordinators, patients, and the European Union for funding.