USMLE-Rx Step 1 Practice Q's

USMLE-Rx Step 1 Qmax Challenge #1384

Check out today’s Step 1 Qmax Question Challenge.

Know the answer? Post it below! Don’t forget to check back for an update with the correct answer and explanation (we’ll post it in the comments section below).

usmle-rx-step-1-qmax-challenge-1384A 2-year-old boy presents to his pediatrician with hepatosplenomegaly, failure to thrive, and progressive central nervous system deterioration. On ophthalmoscopic exam a cherry-red macula is noted. A bone marrow biopsy specimen is shown in the image. The pediatrician suspects that the boy will die by 3 years of age.

Which of the following is the function of the metabolic enzyme deficient in this patient?

A. Converts ceramide trihexoside to lactosyl cerebroside
B. Converts galactocerebroside to cerebroside
C. Converts ganglioside M2 to ganglioside M3
D. Converts glucocerebroside to ceramide
E. Converts sphingomyelin to ceramide


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11 replies »

  1. to USMLE-Rx Step 1 Qmax
    my name is Jeovanny Almanza and I’m getting ready to take the Step 1 examen, but I’m using “First AID for the Basic Sciences General Principle (2017) and I found a mistake related with Nieman Pick disease on the figure 2-109 where we can see the step form sphingomyelin to cerebrosidase, insted of ceramide like we found in “First Aid for yhe USMLE step 1 (2009/2016) please cuold you guy clarified for us this situation ? and Could you know any other critical mistake (like erratum) posible in the book ? and Let us known, I will appreciated your attention, thank you so much


  2. Ceramide tihexoside accumulation is in Fabry disease: angiokeratomas, peripheral neuropathy, renal failure, cardiovascular disease.
    Galactocerebroside accumulation in Krabbe disease: peripheral neuropathy, development delay.
    Ganglioside M2 accumulation in Tay-Sachs disease: cherry-red spot on macula, like in Niemann-Pick disase but no hepatosplenomegaly and foam cells.
    Glucocerebroside accumulation in Gaucher disease: hepatosplenomegaly, osteoporosis, pancytopenia.
    Sphingomyelin accumulation in Niemann-Pick disease: cherry-red spot on macula, hepatosplenomegaly and foam cells.

    So the answer is E.


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