In patients on long-term hemodialysis, it can aggregate into amyloid fibers that deposit in joint spaces, a disease known as dialysis-related amyloidosis.
Mice models deficient for the β2 microglobulin gene have been engineered. These mice demonstrate that β2 microglobulin is necessary for cell surface expression of MHC class I and stability of the peptide binding groove. 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. In the absence of MHC class I, CD8 T cells cannot develop. (CD8 T cells are a subset of T cells involved in the development of acquired immunity.) Low levels of β2 microglobulin can indicate non-progression of HIV.
Levels of beta-2 microglobulin can be elevated in multiple myeloma and lymphoma, though in these cases primary amyloidosis (amyloid light chain) and secondary amyloidosis (Amyloid associated protein) are more common. The normal value of beta-2 microglobulin is <0.2 mg/dL. However, with respect to multiple myeloma, the levels of beta2-microglobulin may also be at the other end of the spectrum. Diagnostic testing for multiple myeloma includes obtaining the beta2-microglobulin level, for this level is an important prognostic indicator. A patient with a level <0.004 g/L is expected to have a median survival of 43 months, while one with a level >0.004 g/L has a median survival of only 12 months.