MSTN and rheumatoid arthritis: Similarly, a study conducted by Lin et al. in China compared the myostatin levels of 344 patients with RA vs. 118 healthy controls and reported higher myostatin levels in the RA group at the baseline of the study (3.241 ± 1.679 ng/mL, vs. 1.717 ± 0.872 ng/mL, respectively; p < 0.001) [62].