Amyloid proteins and amyloidoses: complexity updated.

Amyloid is a beta-pleated fibrillar protein principally constituted of light chains of immunoglobulins (kappa or lambda) in primary or myeloma-associated amyloidosis, of AA proteins in secondary amyloidosis and familial. Mediterranean fever, and of variants of prealbumin - now called transthyretin - in senile amyloidosis and in familial polyneuropathies. Other identified amyloidogenic proteins involve APUD protein derivatives (calcitonin), beta 2 microglobulin in chronic hemodialysis-related amyloidosis and beta protein in Alzheimer disease. After a short review of experimental findings and theories concerning the pathogenesis of amyloid deposition, the clinical aspects of amyloidosis are discussed stressing their great diversity. The diagnostic approach is also examined, with particular emphasis on rectal and kidney biopsy and subcutaneous adipose tissue aspirates. Finally, some comments on the treatment of amyloidosis (role of colchicine and DMSO) are made.