Alcaptonuria

Alcaptonuria (also spelled alkaptonuria) is a rare autosomal recessive inborn error of metabolism caused by a deficiency in the hepatic enzyme homogentisate 1,2-dioxygenase, which disrupts the normal catabolism of phenylalanine and tyrosine Over time, this pigment deposition leads to severe, early-onset ochronotic osteoarthropathy of the spine and weight-bearing joints, as well as complications such as heart valve calcification, nephrolithiasis, and tendon rupture

Alcaptonuria (also spelled alkaptonuria) is a rare autosomal recessive inborn error of metabolism caused by a deficiency in the hepatic enzyme homogentisate 1,2-dioxygenase, which disrupts the normal catabolism of phenylalanine and tyrosine This enzymatic defect leads to the systemic accumulation and urinary excretion of homogentisic acid, which oxidizes into dark benzoquinone acetic acid polymers

This enzymatic defect leads to the systemic accumulation and urinary excretion of homogentisic acid, which oxidizes into dark benzoquinone acetic acid polymers Clinically, it manifests in infancy with urine that darkens upon air exposure, followed by adult-onset ochronosis—characterized by bluish-black pigment deposition in connective tissues

Clinically, it manifests in infancy with urine that darkens upon air exposure, followed by adult-onset ochronosis—characterized by bluish-black pigment deposition in connective tissues

Over time, this pigment deposition leads to severe, early-onset ochronotic osteoarthropathy of the spine and weight-bearing joints, as well as complications such as heart valve calcification, nephrolithiasis, and tendon rupture

Over time, this pigment deposition leads to severe, early-onset ochronotic osteoarthropathy of the spine and weight-bearing joints, as well as complications such as heart valve calcification, nephrolithiasis, and tendon rupture