FORMS OF AMYLOID

• 3 most common forms of amyloid proteins are-

1. AL (amyloid light chain) protein
2. AA (amyloid associated) protein
3. Aβ amyloid
4. Others forms are- TTR, β₂ microglobulin

1. AL protein derived from immunoglobulin light chain.

• AL fibril protein is derived from lambda (λ) light chain (twice more common) than kappa (κ).
• Seen in plasma cell dyscrasias & primarily systemic amyloidosis.

2. AA protein-

• AA fibril protein composed of larger serum precursor (12 kD) called as serum AA.
• It is derived from reticuloendothelial system.
• Seen in secondary amyloidosis as in chronic infectious & autoimmune inflammatory diseases.

3. Aβ amyloid-

• Formed in the cerebral lesions of Alzheimer disease.
• Aβ protein derived from large glycoprotein called amyloid precursor protein.

4. Other forms-

a) TTR (Transthyretin)-

• It is a serum protein synthesized in liver.
• ATTR is a mutant of TTR from amino acids.
• ATTR is deposited in heart of elderly (senile systemic amyloidosis).
• Mutation in the gene encoding TTR may lead to familial amyloid polyneuropathies.

b) Aβ2M (Aβ2- microglobulin)-

• Seen in long term hemodialysis.
• It has predilection for bones & joints.

II) Non- fibrillar components-

1. Amyloid P component
2. Apolipoprotein E (Apo- E)
3. Sulfated glycosaminoglycan (GAGs)

Don’t Forget to Solve all the previous Year Question asked on Forms of Amyloid