[9] In a cytomegalovirus infection, a viral protein binds to β2 microglobulin, preventing assembly of MHC class I molecules and their transport to the plasma membrane.

In fact, in the absence of β2 microglobulin, very limited amounts of MHC class I (classical and non-classical) molecules can be detected on the surface (bare lymphocyte syndrome or BLS).

)[citation needed] In patients on long-term hemodialysis, it can aggregate into amyloid fibers that deposit in joint spaces, a disease, known as dialysis-related amyloidosis.

[13] β2 microglobulin levels cannot, however, distinguish between monoclonal gammopathy of undetermined significance (MGUS), which has a better prognosis, and smouldering (low grade) myeloma.

[citation needed] β2 microglobulin has been shown to be of high relevance for viral entry of Coxsackievirus A9 and Vaccinia virus (a Poxvirus).