Question:easy
Ochronosis is due to the accumulation of which of the following?
Ochronosis is due to the accumulation of which of the following?
Show Hint
Same metabolite that blackens urine on standing in alkaptonuria.
Updated On: Jun 23, 2026
- Homogentisic acid
- Homocysteine
- Xanthurenate
- Glyoxylate
Show Solution
The Correct Option is A
Solution and Explanation
Link the word ochronosis straight to alkaptonuria, the only condition that pigments cartilage and connective tissue a dark bluish-black. The metabolic block is in homogentisate 1,2-dioxygenase, so homogentisic acid piles up. In urine it oxidizes and blackens on standing; in tissue it polymerizes over decades into alkapton pigment that stains intervertebral discs, nasal and ear cartilage, and joints, producing arthritis. That tissue pigmentation is exactly ochronosis, so the accumulating compound is homogentisic acid, option (a). Clear the distractors with their own diseases: homocysteine rises in homocystinuria (lens dislocation and thrombosis), xanthurenate shows up with vitamin B6 deficiency disturbing tryptophan handling, and glyoxylate is tied to primary hyperoxaluria and kidney stones. None pigment connective tissue. Note the original options repeated homogentisic acid twice; replacing the duplicate with homocysteine keeps four real choices and leaves the answer unchanged at (a).
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