HP (Haptoglobin) Gene
Haptoglobin: Genetic Variants, Function, and Clinical Significance
Gene Information Card
| Symbol | HP |
|---|---|
| Full Name | Haptoglobin |
| Gene Type | Protein coding |
| Chromosomal Location | 16q22.2 |
| NCBI Gene ID | 3240 ncbi.nlm.nih.gov/gene/3240 |
| Ensembl ID | ENSG00000257017 |
| UniProt ID | P00738 |
| OMIM ID | 140100 |
| HGNC ID | 5141 |
| Aliases | HP2, HPA1S, HP1, HP2-alpha, HP2-beta |
Description
The HP gene encodes haptoglobin, a plasma glycoprotein that binds free hemoglobin released from erythrocytes, thereby preventing oxidative damage and iron loss. Haptoglobin-hemoglobin complexes are cleared by the reticuloendothelial system. HP has two common alleles (HP1 and HP2) giving rise to three major phenotypes (Hp1-1, Hp2-1, Hp2-2) with distinct functional properties. The gene is primarily expressed in the liver and induced during inflammation.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Hemolytic anemia | Reduced haptoglobin levels due to increased hemoglobin binding and clearance | ClinVar, OMIM |
| Diabetic nephropathy | HP2-2 phenotype associated with increased risk and progression | OMIM, PubMed |
| Cardiovascular disease | HP2-2 variant linked to impaired antioxidant function and increased atherosclerosis risk | OMIM, PubMed |
| Schizophrenia | HP polymorphisms associated with altered immune response and disease susceptibility | OMIM, PubMed |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 185.2 | High |
| Adipose tissue | 12.4 | Medium |
| Lung | 8.1 | Low |
| Kidney | 5.3 | Low |
| Spleen | 4.7 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 | 150.0 | Hepatocyte cell line |
| Huh7 | 130.5 | Hepatocyte cell line |
| A549 | 2.1 | Lung carcinoma cell line |
| K562 | 1.8 | Erythroleukemia cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | Missense | Rare | Loss of start codon, reduced haptoglobin |
| c.49C>T (p.Arg17Cys) | Missense | <0.01% | Altered protein stability |
| HP2 allele duplication | Structural variant | Common (allele frequency ~0.6) | Partial duplication of HP gene, affects multimerization and function |
Mutation functional classification
Loss of Function (LOF)
Loss-of-function mutations (e.g., start codon loss) reduce haptoglobin levels, impairing hemoglobin clearance and increasing oxidative stress.
Gain of Function (GOF)
No well-characterized gain-of-function mutations reported.
Dominant Negative (DN)
HP2 allele produces a variant haptoglobin that forms higher-order multimers, potentially interfering with normal haptoglobin function in heterozygotes.
View complete mutation data：
Gene Ontology (GO)
| • Hemoglobin binding (GO:0030492) | • Serine-type endopeptidase activity (GO:0004252) |
| • Extracellular region (GO:0005576) | • Acute-phase response (GO:0006953) |
| • Iron ion homeostasis (GO:0055072) |
Pathways
• Hemoglobin clearance (Reactome: R-HSA-2168880)
• Innate immune system (Reactome: R-HSA-168249)
• Acute phase response (KEGG: hsa04610)
Protein Summary
Haptoglobin is a 406-amino-acid glycoprotein (UniProt P00738) synthesized as a single-chain precursor and proteolytically cleaved into alpha and beta chains that associate via disulfide bonds. The protein exists as a tetramer (alpha2-beta2) in the Hp1-1 phenotype, while Hp2-2 forms higher-order multimers. Haptoglobin binds free hemoglobin with high affinity, preventing oxidative damage and conserving iron. The HP2 allele results from an internal duplication of exons 3 and 4, leading to a larger alpha chain and altered functional properties.
Related Services
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| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| THPO Knockout HEK293 Cell Line | EDJ-KQ540 | Human | 7066 | Details Get a Quote |
| HPDL Knockout HEK293 Cell Line | EDJ-KQ1214 | Human | 84842 | Details Get a Quote |
| HPSE Knockout HEK293 Cell Line | EDJ-KQ2346 | Human | 10855 | Details Get a Quote |
| SHPK Knockout HEK293 Cell Line | EDJ-KQ2813 | Human | 23729 | Details Get a Quote |
| HPX Knockout HEK293 Cell Line | EDJ-KQ3150 | Human | 3263 | Details Get a Quote |
| HPRT1 Knockout HEK293 Cell Line | EDJ-KQ3913 | Human | 3251 | Details Get a Quote |
| HPCA Knockout HEK293 Cell Line | EDJ-KQ4908 | Human | 3208 | Details Get a Quote |
| HP Knockout HEK293 Cell Line | EDJ-KQ4928 | Human | 3240 | Details Get a Quote |
| HPR Knockout HEK293 Cell Line | EDJ-KQ4929 | Human | 3250 | Details Get a Quote |
| HPN Knockout HEK293 Cell Line | EDJ-KQ4930 | Human | 3249 | Details Get a Quote |
| HPD Knockout HEK293 Cell Line | EDJ-KQ4931 | Human | 3242 | Details Get a Quote |
| HPGD Knockout HEK293 Cell Line | EDJ-KQ4932 | Human | 3248 | Details Get a Quote |
| HPS1 Knockout HEK293 Cell Line | EDJ-KQ4933 | Human | 3257 | Details Get a Quote |
| GRHPR Knockout HEK293 Cell Line | EDJ-KQ6568 | Human | 9380 | Details Get a Quote |
| HPS5 Knockout HEK293 Cell Line | EDJ-KQ6705 | Human | 11234 | Details Get a Quote |
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