INTRODUCTION: Patients with Ehlers Danlos Syndrome are known to have genetically impaired connective tissue and skeletal muscle symptoms in form of pain, fatigue and cramps, however earlier studies have not been able to link these symptoms to morphological muscle changes.

METHODS: We obtained skeletal muscle biopsies in patients with classic EDS (cEDS, n=5 (Denmark)+ 8 (The Netherlands)) and vascular EDS (vEDS, n=3) and analyzed muscle fiber morphology and content (Western blotting and muscle fiber type/area distributions) and muscle mRNA expression and protein synthesis rate (RT-PCR and stable isotope technique).

RESULTS: The cEDS patients did not differ from healthy controls (n = 7-11) with regard to muscle fiber type/area, myosin/α-actin ratio, muscle protein synthesis rate or mRNA expression. In contrast, the vEDS patients demonstrated higher expression of matrix proteins compared to cEDS patients (fibronectin and MMP-2).

DISCUSSION: The cEDS patients had surprisingly normal muscle morphology and protein synthesis, whereas vEDS patients demonstrated higher mRNA expression for extracellular matrix remodeling in skeletal musculature compared to cEDS patients.