GALT Gene: Galactose-1-Phosphate Uridylyltransferase
Genetic variants in GALT cause classic galactosemia, a disorder of galactose metabolism.
Gene Information Card
| Symbol | GALT |
|---|---|
| Full Name | galactose-1-phosphate uridylyltransferase |
| Gene Type | protein coding |
| Chromosomal Location | 9p13.3 |
| NCBI Gene ID | 2592 ncbi.nlm.nih.gov/gene/2592 |
| Ensembl ID | ENSG00000113924 |
| UniProt ID | P07902 |
| OMIM ID | 606999 |
| HGNC ID | 4155 |
| Aliases | GALT, GalT, galactosemia |
Description
The GALT gene encodes galactose-1-phosphate uridylyltransferase, a key enzyme in the Leloir pathway of galactose metabolism. This enzyme catalyzes the conversion of UDP-glucose and galactose-1-phosphate to UDP-galactose and glucose-1-phosphate. Defects in this enzyme lead to classic galactosemia, an autosomal recessive metabolic disorder characterized by an inability to metabolize galactose properly, resulting in toxic accumulation of galactose-1-phosphate and other metabolites.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Classic Galactosemia | Loss-of-function mutations in GALT lead to deficiency of galactose-1-phosphate uridylyltransferase, causing accumulation of galactose-1-phosphate and galactitol, leading to toxic effects in liver, kidney, and brain. | OMIM 230400; ClinVar |
| Galactosemia, Duarte Variant | Specific variants (e.g., p.Asn314Asp) reduce enzyme activity partially, causing a milder form of galactosemia with variable clinical presentation. | ClinVar; PMID: 23430936 |
| Galactosemia, Clinical Variants | Other rare variants (e.g., p.Ser135Leu, p.Gln188Arg) cause varying degrees of enzyme deficiency, leading to classic or variant galactosemia. | ClinVar; PMID: 23430936 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 15.2 | Medium |
| Kidney | 10.5 | Medium |
| Small Intestine | 8.3 | Low |
| Pancreas | 6.1 | Low |
| Brain | 3.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 (liver) | 12.4 | High expression |
| A549 (lung) | 5.6 | Moderate |
| MCF7 (breast) | 3.1 | Low |
| K562 (leukemia) | 2.0 | Low |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| p.Gln188Arg | Missense | ~70% of classic galactosemia alleles in Caucasian populations | Severe enzyme deficiency, classic galactosemia |
| p.Lys285Asn | Missense | Common in African American populations | Severe enzyme deficiency, classic galactosemia |
| p.Ser135Leu | Missense | Rare | Moderate enzyme deficiency, variant galactosemia |
| p.Asn314Asp | Missense | Common in Duarte variant | Partial enzyme activity, milder phenotype |
| c.820+1G>A | Splice site | Rare | Splicing defect, severe enzyme deficiency |
Mutation functional classification
Loss of Function (LOF)
Most pathogenic GALT mutations are loss-of-function, leading to reduced or absent enzyme activity, causing galactosemia.
Gain of Function (GOF)
No gain-of-function mutations have been reported for GALT.
Dominant Negative (DN)
GALT is a homodimer; some missense mutations may exert a dominant-negative effect by interfering with the wild-type subunit, but this is not well established.
View complete mutation data：
Gene Ontology (GO)
| • galactose-1-phosphate uridylyltransferase activity | • UDP-glucose:galactose-1-phosphate uridylyltransferase activity |
| • metal ion binding | • galactose metabolic process |
| • carbohydrate metabolic process |
Pathways
• Galactose metabolism (KEGG: hsa00052)
• Leloir pathway
Protein Summary
The GALT protein is a homodimeric enzyme of 387 amino acids (43 kDa) that catalyzes the second step of the Leloir pathway. It requires a divalent metal ion (e.g., zinc) for activity. The enzyme has two domains: an N-terminal domain involved in substrate binding and a C-terminal domain that interacts with UDP-glucose. Mutations affecting the active site or dimerization lead to enzyme deficiency and galactosemia.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| GALT Knockout HEK293 Cell Line | EDJ-KQ17877 | Human | 2592 | Details Get a Quote |
| GALT Knockout HeLa Cell Line | EDJ-KQ53303 | Human | 2592 | Details Get a Quote |
| GALT Knockout A-549 Cell Line | EDJ-KQ61787 | Human | 2592 | Details Get a Quote |
| GALT Knockout HCT 116 Cell Line | EDJ-KQ70268 | Human | 2592 | Details Get a Quote |
