Biomarkers for Fatigue in Patients with Myasthenia Gravis

Rationale: Myasthenia Gravis (MG) is a chronic autoimmune disease affecting the neuromuscular junction. Although a hallmark of MG is muscle fatigability due to dysfunction of the neuromuscular junction (peripheral fatigue), a large number of MG patients also report symptoms of central or cognitive fatigue. Central fatigue is defined as an experienced lack of energy, physically and/or mentally. In October 2019 we performed a cross-sectional survey study (P15.287) among 420 Dutch MG patients showing a clinically relevant central fatigue rate of 62% on the Checklist Individual Strength-Fatigue subscale (CIS-f). In this prior study, we identified a number of factors associated with fatigue, but these factors cannot fully explain the observed high prevalence of fatigue in MG and very little is known on its biological substrates and pathophysiology.

Objectives: The main objective is to investigate if there are biomarkers for fatigue in MG. The secondary objective is to investigate the muscle origin of these biomarkers.

Study design: This study will be an exploratory study, subdivided in part I and part II (optional).

Study population: Patients with Myasthenia Gravis recruited after previous participation in the cross-sectional fatigue survey study (P15.287).

Intervention:

Phase I:

Visit 1, time: 0

* blood withdrawal * muscle biopsy (not mandatory for participation) * QMG * questionnaires on medication, disease severity, fatigue, depressive symptoms and physical condition

Phase II (optional):

Visit 2, time: 6-12 months after visit 1, after analysis of phase I results.

* blood withdrawal (similar analysis as phase I) * QMG * questionnaires on medication, disease severity, fatigue, depressive symptoms and physical condition