NBME 21 GM2 (NBME Answers)

Retired NBME 21 Answers

nbme21/Block 1/Question#2 (reveal difficulty score)
A 6-month-old girl is brought to the ...
GM2 🔍 / 📺 / 🌳 / 📖
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+63 upvote downvote
submitted by ∗seagull(1933)

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! I hate these with a burning F***ing passion. Thumbs up if you agree

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mcl Amen brother +2

praderwilli Every morning: "I think i'll go over glycogen storage diseases, lysosomal storage diseases, and dyslipidemias after questions this afternoon." Every afternoon: Nah +41

mcl oh my god are you me +3

praderwilli I recently found a program called Pixorize. It's pretty much Sketchy for biochem. Wish I discovered it sooner cuz it has helped for a lot of the painful things like this! +9

burak Cherry red spot basically means niemann-pick or tay sachs. Two differences between is: 1- No HSM in Tay Sachs, HSM in niemann-pick. 2- Both of them has muscle weakness but there is hyperreflexia in Tay Sachs, but areflexia in niemann pick disease. In stem cell HSM is not described and hyperreflexia noted. +5

abhishek021196 What is HSM? +1

mysticsoul HSM - HepatoSplenoMegaly. Cherry red spots think of Tay Sachs, deficient enzyme - HeXosaminidase A, accumulated substrate GM2 ganglioside. Niemann-Pick - Spingomyelinase, Spingomyelin <- which is not even a choice. FA18 Pg 88 +2

lakshmi Dirty USMLE has an incredible video that makes these super easy to get. +4

djeffs1 @lakshmi Link? +1

drdoom @djeffs1 https://www.youtube.com/watch?v=7udUG8KkN_E +1

+8 upvote downvote
submitted by ∗usmleuser007(464)

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1) Very important to note that Tay-Sachs disease has more sensitive startle (moro) reflex in neonates with increased head circumference.

2) Fabry disease = tend to have audio-visual defects w/o liver involvement

3) Niemann-pick disease = anemia & hypotonia with areflexia

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+3 upvote downvote
submitted by ∗isaacyo94(13)

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Nobody has mentioned the super high yield dirtymed video... these mnemonics have saved me countless times... In this case, "a GANG of 6 small jews" helps me remember that Tay-Sachs(six) is a deficiency in the enzyme HEXosaminidase A (six), has an increase in GM2 GANGlioside, and doesn't present with hepatosplenomegaly (small).

https://www.youtube.com/watch?v=7udUG8KkN_E

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madamestep wow thank you that was so helpful! +

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submitted by ∗mcl(671)

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Patient most likely has Tay-Sachs disease. This figure nicely shows the biochemical pathway. Recall that both Tay-Sachs and Neimann Pick disease present with a cherry red spot on fundoscopy, but Tay Sachs lacks the hepatosplenomegaly seen in NP.

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hungrybox Man this is such a nice figure except it doesn't have Krabbe disease :( +1

mcl Here's another one with Krabbe! :) https://epomedicine.com/wp-content/uploads/2017/01/lysosomal-storage-diseases-enzyme-defects.jpg +8

hungrybox thank u +3

drdoom ^ linkify @mcl https://epomedicine.com/wp-content/uploads/2017/01/lysosomal-storage-diseases-enzyme-defects.jpg +

+1 upvote downvote
submitted by ∗basic_pathology(25)

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Since they both have cherry-red spots, two easy ways to differentiate between Tay-Sachs (TS) and Niemann Pick (NP):

(1)liver/spleen: TS: normal ; NP: large

(2) age: TS: <6 months; NP: childhood/adolescence

Bonus: it takes time (older age in NP) to develop hepatosplenomegaly (HSM in NP)

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submitted by awabnaeim(0)

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I think the exaggerated startle in tay sachs is actually due to the hyperacusis, this is mentioned in first aid

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submitted by swandy(3)

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https://media-us.amboss.com/media/thumbs/big_5a95817f72163.jpg

Great figure with all the lysosomal storage diseases!

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submitted by ∗burak(71)

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Cherry red spot basically means niemann-pick or tay sachs. Two differences between is: 1- No HSM in Tay Sachs, HSM in niemann-pick. 2- Both of them has muscle weakness but there is hyperreflexia in Tay Sachs, but areflexia in niemann pick disease. In stem cell HSM is not described and hyperreflexia noted.

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burak i mean, hyperacusis+hyperreflexia+sensitive startle +2

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