CD79A and Miyoshi myopathy: Lower levels of specific SARS-CoV-2 IgA antibodies were detected in all groups, and 33% (5/15), 23% (5/22), and 80% (8/10) of MGUS, SMM, and MM did not develop any specific IgA antibodies, respectively (Fisher’s exact test P = 0.008, Fig 2B).