Expression of sialylated NCAM in muscle of HIBM patients. A. Muscle from two control individuals exhibit NCAM mobility consistent with a higher molecular weight, indicative of sialylation. N1 is normal and N2 has sporadic IBM; note increased NCAM in this person's muscle. The muscle of patient 1 also has an increased amount of NCAM; patients 2 and 4 have moderate amounts of NCAM. The NCAM of the HIBM patients migrates with greater mobility than normal, indicating lack of sialylation. The amount of muscle NCAM decreased after (Post) compared with before (Pre) IVIG treatment in patients 1 and 2, but increased in patient 4. B. Sialidase treatment increased the mobility of control muscle (N1 and N2). The mobility of muscle NCAM was not altered by sialidase treatment in patient 2, but it was increased by sialidase treatment in patient 1.