Amyloidosis Flashcards
(24 cards)
APrP amyloid
Derived from prion proteins (spongiform encephalopathies such as Creutzfeldt-Jakob and Mad Cow)
ACal amyloid
Derived from procalcitonin, found in medullary carcinoma of thyroid (from thyroid C cells)
What is a classic feature of amyloidosis?
Glossomegaly
What blood disorder may develop as a result of amyloidosis and why?
Coagulopathy, because of selective absorption of factor X by amyloid protein
Amyloid consists of what two components?
Amyloid P (a component of normal basement membranes) and a disease-specific fibrillogenic protein
How do amyloid deposits appear histologically?
Amorphous, acellular, eosinophilic, extracellular deposits
What stain is used to detect amyloid and what do they look like under polarized light?
Congo red makes them red-orange, and they have an apple green birefringence under polarized light
What stain causes auto-fluorescence of amyloid when viewed with ultraviolet light?
Thioflavin T
What tertiary structure is common to all forms of amyloid?
Beta-pleated sheet
Where is amyloid typically deposited first?
Around subendothelial basement membranes
How do organs with significant amyloid appear grossly?
Pale and firm (due to lack of circulation)
What are the categories in the old scheme of amyloidosis classification?
Primary, secondary, familial, and isolated
Why is primary amyloidosis called primary and what is it associated with?
Associated with plasma cell disorder, symptoms related to amyloid deposition occur prior to diagnosis of plasma cell disorder
Why is secondary amyloidosis called secondary and what is it associated with?
Associated with persistent inflammatory disorder (eg rheumatoid arthritis), which is diagnosed before the amyloidosis
Familial Mediterranean fever
Autosomal recessive amyloidosis characterized by neutrophil disfunction (yields recurrent infections and secondary amyloidosis)
Familial amyloidotic polyneuropathy
Autosomal dominant amyloidosis caused by point mutations in transthyretin gene (yields pierpheral and autonomic neuropathies)
Why do Down syndrome patients tend to get early onset Alzheimer?
Because the gene for amyloid b protein precursor is located on chromosome 21
What composes amyloid deposits in arteries and what is this fragment cleaved from?
Lactadherin, which is cleaved from medin
Which amyloidosis is related to type 2 diabetes?
Amylin, which is islet amyloid polypeptide (oversynthesized by B islet cells in type 2 diabetics)
Senile cardiac amyloidosis
A typically asymptomatic form of cardiac amyloidosis (composed of transthyretin) seen in older men
AL amyloid
Derived from immunoglobulin light chains (esp lambda) and seen with plasma cell disorders and b-cell lymphomas (primary amyloidosis)
AA amyloid
Derived from serum amyloid A (acute phase reactant), seen in inflammatory states (secondary amyloidosis)
AB2M amyloid
Derived from B2-microglobulin (renal failure), leads to destructive arthropathy in dialysis pts
AB amyloid
Derived from B protein (Alzheimer)
