CLDN19: Claudin 19
Tight junction protein implicated in renal magnesium wasting and ocular disorders
Gene Information Card
| Symbol | CLDN19 |
|---|---|
| Full Name | Claudin 19 |
| Gene Type | protein-coding |
| Chromosomal Location | 1p34.2 |
| NCBI Gene ID | 149461 ncbi.nlm.nih.gov/gene/149461 |
| Ensembl ID | ENSG00000164007 |
| UniProt ID | Q8N6F1 |
| OMIM ID | 610036 |
| HGNC ID | 2040 |
| Aliases | claudin-19, FLJ90067 |
Description
CLDN19 encodes claudin-19, a member of the claudin family of tight junction proteins. Claudin-19 is essential for paracellular ion transport in the renal thick ascending limb of Henle, particularly for magnesium and calcium reabsorption. It also plays a role in maintaining the blood-retinal barrier. Mutations in CLDN19 cause familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) with ocular involvement.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) with ocular involvement | Loss-of-function mutations disrupt paracellular Mg2+ and Ca2+ reabsorption in the kidney, leading to renal wasting, nephrocalcinosis, and progressive renal failure. Ocular manifestations include coloboma and myopia. | OMIM #248190; ClinVar; PMID 16783384 |
| Ocular coloboma | CLDN19 mutations impair tight junction integrity in the retinal pigment epithelium, causing developmental eye defects. | OMIM #610036; PMID 16783384 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Kidney | 12.5 | High |
| Eye (retina) | 8.2 | Medium |
| Liver | 2.1 | Low |
| Testis | 1.8 | Low |
| Brain | 0.5 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 15.3 | High expression in transfected cells |
| ARPE-19 (retinal pigment epithelium) | 9.7 | Endogenous expression |
| HK-2 (proximal tubule) | 11.4 | Endogenous expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.59G>A (p.Gly20Asp) | Missense | Found in FHHNC families | Loss of function; disrupts tight junction strand formation |
| c.71G>A (p.Gly24Arg) | Missense | Rare | Impaired paracellular ion selectivity |
| c.157C>T (p.Arg53Trp) | Missense | Reported in ocular coloboma | Dominant negative effect on barrier function |
Mutation functional classification
Loss of Function (LOF)
Most CLDN19 mutations are loss-of-function, reducing paracellular Mg2+ and Ca2+ permeability in the kidney.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
Some missense mutations (e.g., p.Arg53Trp) exhibit dominant-negative effects on tight junction assembly.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Tight junction (KEGG: hsa04530)
• Paracellular ion transport (Reactome: R-HSA-420029)
Protein Summary
Claudin-19 is a 224-amino-acid transmembrane protein with four transmembrane domains, two extracellular loops, and intracellular N- and C-termini. It forms tight junction strands that regulate paracellular ion permeability. In the kidney, claudin-19 interacts with claudin-16 to form a cation-selective pore for Mg2+ and Ca2+ reabsorption. In the eye, it contributes to the blood-retinal barrier. The protein is predominantly expressed in renal tubules and retinal pigment epithelium.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CLDN19 Knockout HEK293 Cell Line | EDJ-KQ11118 | Human | 149461 | Details Get a Quote |
| CLDN19 Knockout HeLa Cell Line | EDJ-KQ58629 | Human | 149461 | Details Get a Quote |
| CLDN19 Knockout A-549 Cell Line | EDJ-KQ67111 | Human | 149461 | Details Get a Quote |
| CLDN19 Knockout HCT 116 Cell Line | EDJ-KQ75518 | Human | 149461 | Details Get a Quote |
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