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NBME 24 Answers

nbme24/Block 4/Question#29

A 56-year-old man has a 3-year history of ...

Presenilin

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 +8  upvote downvote
submitted by neonem(227),

Per Pathoma: early inherited cases of Alzheimer's dementia are associated with mutations in presenilin-1/presenilin-2, as well as Down's syndrome. Down's would be due to an extra chromosome 21, which carries the gene for amyloid precursor protein (APP). Extra APP is converted to A-beta amyloid and this forms extracellular neuritic plaques, a prominent feature of Alzehimer's.

Important to not confuse Amyloid A protein (one of the answer choices) with Amyloid precursor protein. Deposition of AA amyloid is more associated with chronic inflammatory states, malignancy, and Familial Mediterranean Fever. Beta-2 microglobulin is another amyloid association: dialysis-associated (deposits in joints)


 +3  upvote downvote
submitted by yotsubato(210),

Amyloid A : seen in chronic inflammatory conditions, deposition of amyloid in tissues

B2 microglobulin: associated with ESRD and long term dialysis

Neurofilament protein: Form the cytoskeleton of neurons (in healthy individuals)

Presenilin: associated with familial alzheimers disease