<prompt> Calcification of interveebral disc is a feature ofAnkylosing spondylitisHyperparathyroidismCharcots diseaseAlkaptonuria  <response>: xray of ochronosis in alkaptonuria is seen symtpoms of alkaptonuria : SYMPTOMS Urine becomes black when exposed to air. Osteoahritis mainly spine, hips, shoulders and knees. Black spots in the sclera of the eye Ochronosis. Discolored ear and dark earwax. Hea valves are affected by the accumulation of HGA. Blue-black speckled discoloration of the skin. Kidney, prostate and bladder stones due to the build-up of HGA in the genito-urinary tract, during urine production. ref : maheswari 9th ed 