MUSK and myasthenia gravis: To address the potential of ITIH3 serving as a biomarker enabling patient stratification, we next investigated whether increase in ITIH3 levels could also be observed in MG patients without anti-AChR-Abs, such as anti-MuSK-Ab-positive and seronegative MG patients (n = 10 each) (for further clinical and demographic baseline data, see Suppl.