Alkaptonuria in a middle-aged female.

Area of Science:

• Biochemistry
• Genetics
• Rheumatology

Background:

• Alkaptonuria (AKU) is a rare autosomal recessive metabolic disorder.
• It stems from a deficiency in the homogentisate 1,2 dioxygenase (HGD) enzyme.
• This deficiency leads to the accumulation of homogentisic acid (HGA).

Observation:

• A 54-year-old woman in Tehran presented with hip and lumbar spine pain.
• Symptoms included urine darkening and scleral/ear discoloration, developing over 12 years.
• Imaging revealed degenerative spinal changes and chondrocalcinosis.

Findings:

• Urine darkened upon exposure to air or bicarbonate.
• Elevated HGA levels in urine confirmed Alkaptonuria.
• The patient's sister also had a history of undiagnosed back pain.

Implications:

• Alkaptonuria should be considered in patients with low back pain, especially with a family history.
• Bluish discoloration of cartilage tissues is a potential diagnostic indicator.
• Timely diagnosis can aid in managing the progressive arthropathy associated with AKU.