A patient presents with progressive ataxia, cherry-red spot on macula, splenomegaly, and foam cells on bone marrow biopsy. Glucocerebrosidase (acid beta-glucosidase) activity is markedly reduced. The lipid that accumulates in Gaucher's disease and the sphingoid base backbone of this glycosphingolipid are:

• A Galactocerebroside; phytosphingosine backbone
• B Glucocerebroside (glucosylceramide); sphingosine backbone ✓
• C GM2 ganglioside; sphinganine (dihydrosphingosine) backbone
• D Ceramide; sphingomyelin backbone

Explanation

Gaucher's disease (type I most common) involves deficiency of acid beta-glucosidase (glucocerebrosidase), causing accumulation of glucosylceramide (glucocerebroside) in macrophages of liver, spleen, and bone marrow (Gaucher cells). The sphingoid base of ceramide is sphingosine (trans-4-sphingenine, an 18-carbon amino alcohol). Gaucher cells have a 'crumpled tissue paper' cytoplasm appearance. The cherry-red spot occurs only in neuronopathic types II and III (not type I). Treatment with enzyme replacement therapy (imiglucerase) or substrate reduction therapy (miglustat/eliglustat) is available. Tay-Sachs involves GM2 accumulation; Krabbe disease involves galactocerebroside.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.