kiranmayi
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A four-year-old white female presents to the pediatric clinic for follow-up due to developmental delay. Her medical history reports frequent episodes of otitis media, bronchitis, and pneumonia. Physical examination reveals coarse facial features, gingival hypertrophy, joint stiffness, claw hand deformity, and generalized hypotonia. Significant motor delay is appreciated. Electron microscopy of muscle biopsy demonstrates numerous intracytoplasmic inclusions, which are membrane-bound vacuoles filled with fibrillogranular material. I-cell disease is suspected. What is the function of the deficient enzyme?
A. Breakdown of dermatan sulfate and heparan sulfate
B. Cleavage of disaccharides
C. Cleavage of fructose
D. Degradation of sphingolipids
E. Metabolism of galactose
F. Phosphorylation of mannose residues
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| asmi
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D........
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| mjl1717
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phosphorylation of mannose
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| Idiopathic
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Yep. I cell disease involves lack of phosphorylation of mannose residues (to mannose-6-phosphate) in the Golgi, and the enzymes are all either secreted or degraded before they can be stored in lysosomes.
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| asmi
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What a great mistake...my apology... :oops:
Its phosphorylation of mannose residues.
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| kiranmayi
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Ans is F. Phosphorylation of mannose residues
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