The different types of amyloidosis
Amyloidosis is a disease characterized by the abnormal deposition of amyloid protein in tissues and organs. Amyloidosis can affect any organ or tissue in the body, but most commonly affects the heart, kidneys, liver, and nerves. There are four main types of amyloidosis: primary systemic amyloidosis, secondary systemic amyloidosis, familial amyloidosis, and localized amyloidosis.
Primary systemic amyloidosis (AL) is the most common type of amyloidosis, accounting for approximately 85% of all cases. AL is caused by a plasma cell disorder, such as multiple myeloma or monoclonal gammopathy of undetermined significance (MGUS). In AL, abnormal plasma cells produce an excess of immunoglobulin light chains that deposit in tissues and organs throughout the body. AL typically affects the heart, kidneys, liver, and nervous system.
Secondary systemic amyloidosis (AA) occurs when another chronic inflammatory disease causes excess production of proteins that deposit as amyloid in tissues and organs. The most common form of AA is associated with rheumatologic diseases such as rheumatoid arthritis or Crohn’s disease.
Familial amyloidoses are rare inherited disorders caused by mutations in certain genes that lead to production of abnormal proteins that deposit as amyloid in tissues and organs. The most common form of familial amyloidosis is transthyretin-associated familial amyloidosis, which is caused by mutations in the TTR gene.
Localized amyloidosis involves deposits of amyloid protein in localized areas of the body, such as the skin, tongue, eyes, and joints. This type of amyloidosis is typically associated with inflammation due to an infection or injury.
