This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy of Bone & Fracture Healing, Subject name: Orthopaedics
What change will be seen in vertebral column in ochronosis- 
Select and explain. 
A. Calcification of disc, B. Bamboo spine, C. Increased disc space, D. None
A: Calcification of disc
Answer: A: Calcification of disc 
Explanation: Ans. is 'a' i.e., Calcification of discAlkaptonuria# It is due to deficiency of homogentisate oxidase. As a result homogentisic acid (homogentisate) is excreted execessively in urine, There are three important characteristic features in alkaptonuria-Urine becomes dark after being exposed to air. It is due spontaneous oxidation of homogentisate into benzoquinone acetate, which polvmerse to form black-brown pigment alkapton which imparts a characteristic black-brown colour to urine.Alkapton deposition occurs in sclera, ear, nose, cheeks and intervertebral disc space. A condition called ochronosis. There may be calcification of intervertebral discs.Onchronosis arthritis affecting shoulder, hips, knee.# Benedict's test is strongly positive in urine and so is the ferric chloride (FeClyl test. Benedict's reagent gives a greenish brown precipitate with brownish black supematent. Feh ling's reagent (FeClj gives blue green colour.