Among the pathogenic mutations studied here, only the S85C mutation significantly affected MATR3(∆RRM2)-EGFP droplet viscosity; notably, S85C is also the only disease-associated mutation associated with a primary myopathy as well as neurodegeneration (Feit et al., 1998; Senderek et al., 2009). The gene discussed is MATR3; the disease is myopathy.