HAL: Histidine Ammonia-Lyase
Gene encoding histidine ammonia-lyase, involved in histidine catabolism and associated with histidinemia.
Gene Information Card
| Symbol | HAL |
|---|---|
| Full Name | Histidine Ammonia-Lyase |
| Gene Type | protein-coding |
| Chromosomal Location | 12q23.1 |
| NCBI Gene ID | 3034 ncbi.nlm.nih.gov/gene/3034 |
| Ensembl ID | ENSG00000111224 |
| UniProt ID | P42357 |
| OMIM ID | 609457 |
| HGNC ID | 4802 |
| Aliases | HISTIDASE, HIS |
Description
The HAL gene encodes histidine ammonia-lyase, an enzyme that catalyzes the first step in histidine catabolism, converting L-histidine to urocanic acid. Mutations in HAL cause histidinemia, an autosomal recessive disorder characterized by elevated histidine levels in blood and urine, often benign but occasionally associated with intellectual disability or speech delay.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Histidinemia | Loss-of-function mutations in HAL reduce histidine ammonia-lyase activity, leading to accumulation of histidine and its metabolites. | ClinVar, OMIM |
| Urocanic Aciduria | Deficiency of HAL results in decreased urocanic acid production; rare metabolic condition. | OMIM |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 12.5 | High |
| Skin | 8.3 | Medium |
| Kidney | 4.1 | Low |
| Small Intestine | 3.0 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 | 15.2 | Hepatocellular carcinoma cell line |
| HaCaT | 9.8 | Keratinocyte cell line |
| HEK293 | 2.1 | Embryonic kidney cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.716C>T (p.Pro239Leu) | Missense | Rare | Reduced enzyme activity; associated with histidinemia |
| c.1045G>A (p.Gly349Arg) | Missense | Rare | Loss of function; reported in histidinemia patients |
| c.1270C>T (p.Arg424*) | Nonsense | Very rare | Premature stop; likely pathogenic |
Mutation functional classification
Loss of Function (LOF)
Most reported HAL mutations are loss-of-function, leading to histidinemia.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations reported.
View complete mutation data：
Gene Ontology (GO)
| • histidine ammonia-lyase activity (GO:0004397) | • histidine catabolic process (GO:0006548) |
| • cytoplasm (GO:0005737) |
Pathways
• Histidine metabolism (KEGG: hsa00340)
• Metabolic pathways (KEGG: hsa01100)
Protein Summary
Histidine ammonia-lyase (HAL) is a homotetrameric enzyme that converts L-histidine to trans-urocanic acid and ammonia. It requires a 3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO) prosthetic group derived from the autocatalytic cyclization of an alanine-serine-glycine tripeptide. The enzyme is primarily expressed in liver and skin, where it regulates histidine levels and contributes to UV-induced immunosuppression via urocanic acid.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| HAL Knockout HEK293 Cell Line | EDJ-KQ4840 | Human | 3034 | Details Get a Quote |
| HAL Knockout HCT 116 Cell Line | EDJ-KQ27623 | Human | 3034 | Details Get a Quote |
| HAL Knockout HeLa Cell Line | EDJ-KQ53489 | Human | 3034 | Details Get a Quote |
| HAL Knockout A-549 Cell Line | EDJ-KQ61961 | Human | 3034 | Details Get a Quote |
