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Commit #2864172022 (Medical sciences) 26
22. What protein is involved in amyloidosis associated with dialysis?
a. Serum amyloid Ab. Beta 2 microglobulin
c. Transthyretin
d. Light chains
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Commit #286417a. Serum amyloid A - AA amyloidosis secondary to inflammation
b. Beta 2 microglobulin - seen in dialysis related amyloidosis
c. Transthyretin - ATTR - CM
d. Light chains - AL - CM, MM
d. Light chains - AL - CM, MM
CARDIAC AMYLOIDOSIS = extracellular deposition of misfolded proteins in the ventricular myocardium → progressive infiltrative disease assoc. with restrictive cardiomyopathy.
Histological = green birefringence when viewed under cross-polarised light after staining with Congo Red.
9 different types of cardiac amyloidosis but 95% of cases are:
1. Transthyretin amyloidosis (ATTR) - transthyretin aka prealbumin produced by the liver > hereditary (ATTRv) →AD inheritance with incomplete penetrance
> acquired (ATTRwt) → assoc. with aging .˙. most frequent
2. Monoclonal immunoglobulin light chain amyloidosis (AL) → plasma cells cooked
Other problematic proteins:
β-2 microglobulin - In patients on long-term hemodialysis, it can aggregate into amyloid fibers that deposit in joint spaces, a disease, known as dialysis-related amyloidosis (DRA)
- Hemodialysis is effective at removing larger molecules, but β2M is small and it does not efficiently pass through the dialysis membrane used in traditional dialysis .˚. Long-term dialysis patients accumulate high levels of β2M because it is poorly cleared by standard dialysis techniques. Accumulated B2M misfolds into amyloid fibrils and deposits.
- Newer high-flux dialysis membranes can better clear β2M and reduce accumulation. Renal transplant also helps lol
Serum amyloid A - causes AA amyloidosis (also called secondary amyloidosis)
- SAA is an acute-phase protein produced mainly by the liver in response to inflammation, infection, or tissue injury.
- In chronic inflammatory diseases (such as rheumatoid arthritis, inflammatory bowel disease, tuberculosis, familial Mediterranean fever), elevated levels of SAA are sustained over time.
- Prolonged elevated SAA levels lead to the misfolding of the protein. This misfolded SAA forms amyloid fibrils, which deposit in various tissues throughout the body.
- In AA amyloidosis, the kidneys are most commonly affected, leading to nephrotic syndrome (swelling, protein loss in urine, and kidney failure). Mx is to treat the underlying condition to reduce the level of inflammation