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Card
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Title
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Homocystinuria
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ImagePath
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System
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amino acid metabolism − methionine/homocysteine
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Overview
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AR cystathionine β‑synthase (most common) or methionine synthase defects → ↑ homocysteine.
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Pathophysiology
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Homocysteine damages endothelium & connective tissue → thrombosis & Marfanoid habitus.
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Presentation
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Tall stature, lens subluxation (down/in), intellectual disability, osteoporosis, recurrent DVT/TE.
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Diagnosis
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↑ homocysteine & methionine; positive cyanide‑nitroprusside urine test; CBS sequencing.
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Management
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Pyridoxine high dose, restriction of Met, supplement B₁₂ and folate; betaine for remethylation.
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Epidemiology
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≈1 : 200 000; B₆‑responsive in 50 %.
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Tags
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