Compared to naïve B cells (IgD+CD27−), memory B cells showed increased MM, with class-switched memory B cells (IgD-CD27+), pre-switched memory B cells (IgD+CD27+), which predominantly secrete IgM and late resting or double negative memory cells (26) (IgD-CD27−) also showing a significant increase in MM. Here, CD27 is linked to Miyoshi myopathy.