Substances	Interaction	Organism	Category

Substances	Interaction	Organism	Category

     histidinemia At least four mutations in the HAL gene have been found to cause histidinemia. All of these mutations change single amino acids in the histidase enzyme. These mutations are thought to decrease or eliminate enzyme activity, resulting in an inability to break down histidine. Histidine that is not broken down accumulates in the blood, but it typically causes no health problems.

     The HAL gene provides instructions for making an enzyme called histidase. Histidase breaks down the amino acid histidine, a building block of most proteins. Histidase is active (expressed) primarily in the liver and the skin. This enzyme breaks down histidine to a molecule called urocanic acid. In the liver, urocanic acid is broken down to form another amino acid called glutamic acid. In the skin, urocanic acid is involved in the response to ultraviolet (UV) light.

Condition	Change (log2fold)	Comparison	Species	Experimental variables	Experiment name

Condition	Change (log2fold)	Comparison	Species	Experimental variables	Experiment name

The following transcription factors affect gene expression:

• GR
• GR-alpha
• GR-beta
• NF-kappaB1
• Nkx2-5
• PPAR-alpha
• NF-1

Molecular Function:

• Histidine Ammonia-Lyase Activity

Biological Processes:

• Histidine Catabolic Process
• Histidine Catabolic Process To Glutamate And Formamide
• Histidine Catabolic Process To Glutamate And Formate

Drug Bank:

• L-Histidine

*synonyms