crista
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An adolescent female develops hemiballismus (repetitive throwing motions of the arms) after anesthesia for a routine operation. She is tall and lanky, and it is noted that she and her sister both had previous operations for dislocated lenses of the eyes. The symptoms are suspicious for the disease homocystinuria (236300). Which of the following statements is descriptive of this disease?
A. Patients may be treated with dietary supplements of vitamin B12
B. Patients may be treated with dietary supplements of vitamin C
C. There is deficient excretion of homocysteine
D. There is increased excretion of cysteine
E. There is a defect in the ability to form homocysteine from methionine by methylation
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| rida
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I think its E
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| Gul
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A
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| rida
Forum Guru
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Don't they need Vitamin B6 as cystathionine synthase requires that as a cofactor......
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| DiaHuq
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a?
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| crista
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the given answer was E but i thought it's wrong bz homocysteine can be synthetised but not cystatione...may be someone could clarify this.
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| mjl1717
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Can be caused by deficiency in
1)Cystathionine B synthatase
2)Homocysteine methyl transferase
3)folate
4)B12
5)B6
6)precursors of homocysteine are s -adenosylhomocysteine and SAM
7)homocysteine is a precursor to methionine
8)methionine is precursor to SAM
9)homocysteine needs B12 ,folate with Homocysteine methyl transferase to form methionine
10)*so B12 could be used to treat milder forms of homocysteinuria
hope this helps
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| Sakaki-
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Yeah, E looks wrong to me as well; homocystinuria is due to a defect in the transsulfuration or remethylation (of homocysteine to methionine) step. I think that B12 would be used as treatment since it is a cofactor for methionine synthase.
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