Alkoptonuria by

Genetic Disorder

russelgw — 2025-04-03 15:20:19 UTC

Recessive trait. Very rare. 1 in 250,000 births. Affects HGD gene which codes for the enzyme Homogentisate 1,2-Dioxygenase. Affects males and females equally.

Buildup of Homogentisic Acid (HGA)

russelgw — 2025-04-03 15:22:56 UTC

The affected HGD gene leads to an extreme buildup of homogentisic acid. It is 2,000 times the normal amount in someone with this disease.

Dark Urine

russelgw — 2025-04-03 18:49:53 UTC

Urine is typically abnormally dark, as well as turns black when left standing in the open air for several hours.

Arthritis of Large Joints

russelgw — 2025-04-03 18:51:45 UTC

Mainly effects the spine. Radiographs of the spine showing flattened and calcified intervertebral discs are pathognomonic. Can lead to total fusion of the vertebral discs.

Gas Chromatography Mass Spectroscopy

saliud — 2025-04-06 10:30:29 UTC

The amount of homogentisic acid in the 24-hour urine is detected via gas chromatography-mass spectrometry (GC-MS) analysis.

Biochemical Test

saliud — 2025-04-06 11:20:45 UTC

Several lab diagnoses such as biochemical, hematological, and histology. The urine test for HGA is the gold-standard test to diagnose alkaptonuria

Visible buildup of acid in cartilage and eyes

russelgw — 2025-04-07 17:16:36 UTC

The acid has nowhere to go so it builds up in strange places. Usually doesn't start to occur until later in life (typically over 30 y/o).

Signs in Infants

falbeb1 — 2025-04-13 17:28:34 UTC

Diapers may stain black when exposed due to air exposure. This is often missed by parents.

HGA Detection in Urine

falbeb1 — 2025-04-13 17:38:01 UTC

Earlies form of detection available for Alkoptonuria. Can be detected in pediatrics, but is not included in routine urinalysis unless suspected by a physician.

Connective Tissue Degradation

falbeb1 — 2025-04-13 18:02:42 UTC

Condition causes connective tissue to breakdown through the accumulation of HGA pigment oxidizing. Can lead to aortic stenosis and arthritis.

Knee joint

saliud — 2025-04-13 23:44:48 UTC

Alkaptonuria can lead to ochronosis, where a buildup of homogentisic acid (HGA) causes pigmentation and cartilage degeneration in the knee joint. Over time, this results in chronic joint pain, stiffness, and early-onset osteoarthritis, significantly impacting mobility.

Genetic testing

saliud — 2025-04-14 01:10:13 UTC

Genetic testing can identify mutations in the HGD gene that are associated with alkaptonuria

Buildup of homogentisic acid in cartilage

russelgw — 2025-04-14 01:17:52 UTC

What does Homogentisate 1,2-Dioxygenase do?

russelgw — 2025-04-14 01:32:59 UTC

This enzyme is involved in the metabolism of amino acids phenylalanine and tyrosine. During their breakdown a toxic substance, homogentisic acid, is produced. without enough Homogentisate 1,2-Dioxygenase, this molecule can't be moved to the next step and it builds up in the body.