Defect in alkaptonuria is:

Ans: c (Deficiency of homo gentisic acid oxidase) Ref: Vasudevan, 4th ed, p. 192Alkaptonuria is an AR condition. Metabolic defect is deficiency of homogentisic acid oxidase.Features:Excretion of homogentisic acid in urine.Blackening of urine on standing.By 3rd or 4th decade, patient develops backache due to ochronosis.Ochronosis is deposition of alkaptone bodies in cartilages like inter vertebral disc.Radiologically parrot beak appearance.Treatment is decreased protein intake with phenylalanine.Ferric chloride test is positive.Benedict's test also positive in urine.