SLC9A6 (NHE6): Sodium/Hydrogen Exchanger 6 in Christianson Syndrome and Neurodevelopmental Disorders
A comprehensive biomedical reference for SLC9A6, encoding the endosomal Na+/H+ exchanger NHE6, with emphasis on its role in X-linked intellectual disability, Christianson syndrome, and neuronal pH regulation.
Gene Information Card
| Symbol | SLC9A6 |
|---|---|
| Full Name | Solute carrier family 9 member A6 |
| Gene Type | Protein coding |
| Chromosomal Location | Xq26.3 |
| NCBI Gene ID | 10479 ncbi.nlm.nih.gov/gene/10479 |
| Ensembl ID | ENSG00000198689 |
| UniProt ID | Q92581 |
| OMIM ID | 300231 |
| HGNC ID | 11079 |
| Aliases | NHE6, KIAA0267, MGC126562, MGC126564 |
Description
SLC9A6 encodes sodium/hydrogen exchanger 6 (NHE6), a pH regulator localized primarily to early and recycling endosomes. It mediates electroneutral exchange of Na+ for H+ across endosomal membranes, playing a critical role in maintaining luminal pH homeostasis, endosomal trafficking, and neuronal function. Mutations in SLC9A6 cause Christianson syndrome, an X-linked neurodevelopmental disorder characterized by intellectual disability, epilepsy, ataxia, and microcephaly. The gene is ubiquitously expressed with high levels in brain, particularly in neurons, and is involved in synaptic vesicle recycling and autophagy.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Disease | Mechanism | Evidence |
| Christianson syndrome | Loss-of-function mutations (nonsense, frameshift, splice-site) lead to NHE6 deficiency, causing endosomal acidification defects, impaired neuronal trafficking, and neurodegeneration. | ClinVar, OMIM (300243), multiple case reports |
| X-linked intellectual disability | Pathogenic variants in SLC9A6 disrupt endosomal pH regulation, affecting synaptic plasticity and cognitive function. | OMIM, HGMD, literature |
| Epilepsy (often associated with Christianson syndrome) | NHE6 dysfunction alters neuronal excitability and synaptic transmission, contributing to seizure phenotypes. | ClinVar, case studies |
| Autism spectrum disorder (in some patients) | SLC9A6 mutations may contribute to ASD features through shared neurodevelopmental pathways. | ClinVar, research articles |
| Angelman syndrome-like phenotype | Some SLC9A6 mutations present with features overlapping Angelman syndrome (e.g., ataxia, happy demeanor), due to similar endosomal dysfunction. | ClinVar, case reports |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Tissue | nTPM | Level |
| Brain (cerebral cortex) | ~30 | High |
| Cerebellum | ~25 | High |
| Heart | ~15 | Medium |
| Kidney | ~12 | Medium |
| Liver | ~8 | Low |
| Lung | ~6 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| Cell Line | nTPM | Notes |
| SH-SY5Y (neuroblastoma) | ~35 | High expression; used for neuronal studies |
| HeLa (cervical carcinoma) | ~20 | Moderate expression |
| HEK293 (embryonic kidney) | ~18 | Moderate expression; common for transfection |
| HepG2 (hepatocellular carcinoma) | ~10 | Low expression |
| A549 (lung carcinoma) | ~8 | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| Variant | Type | Frequency | Effect |
| c.1092_1093del (p.Glu365Aspfs*3) | Frameshift | Rare (found in multiple families) | Loss of function; truncated protein, likely degraded |
| c.1264C>T (p.Arg422*) | Nonsense | Rare | Loss of function; premature stop codon |
| c.1568+1G>A | Splice-site | Rare | Loss of function; aberrant splicing, likely exon skipping |
| c.1696C>T (p.Arg566Trp) | Missense | Rare | Uncertain; may affect protein stability or function |
| c.2146G>A (p.Gly716Arg) | Missense | Rare | Uncertain; possibly hypomorphic |
Mutation functional classification
Loss of Function (LOF)
Most pathogenic SLC9A6 mutations are loss-of-function, including nonsense, frameshift, and splice-site variants that lead to NHE6 protein truncation or absence, resulting in endosomal pH dysregulation and Christianson syndrome.
Gain of Function (GOF)
No gain-of-function mutations have been reported for SLC9A6 in the literature or databases.
Dominant Negative (DN)
Given the X-linked inheritance and hemizygosity in males, dominant-negative effects are not typically described; however, some missense variants might exert a dominant-negative effect in females due to X-inactivation skewing, but evidence is limited.
View complete mutation data：
Gene Ontology (GO)
| • Sodium:proton antiporter activity | • Potassium:proton antiporter activity |
| • Endosome membrane | • Early endosome |
| • Recycling endosome | • Neuronal cell body |
| • Dendrite | • Axon |
| • pH regulation | • Endosomal transport |
| • Synaptic vesicle recycling | • Autophagy |
Pathways
• Endosomal acidification and trafficking
• Neurotransmitter release and synaptic vesicle recycling
• Autophagy pathway
• mTOR signaling (indirectly via amino acid sensing)
Protein Summary
NHE6 (Na+/H+ exchanger 6) is a 701-amino acid multi-pass transmembrane protein with 10-12 predicted transmembrane helices. It localizes to early and recycling endosomes, where it catalyzes the electroneutral exchange of Na+ for H+, thereby regulating endosomal pH. NHE6 has a long cytoplasmic C-terminal tail containing PDZ-binding motifs that mediate protein-protein interactions. It is highly expressed in neurons, where it is essential for maintaining proper endosomal pH during synaptic vesicle recycling and receptor trafficking. Defects in NHE6 lead to endosomal hyperacidification, impaired neuronal function, and neurodegeneration.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SLC9A6 Knockout HEK293 Cell Line | EDJ-KQ7057 | Human | 10479 | Details Get a Quote |
| SLC9A6 Knockout HeLa Cell Line | EDJ-KQ18240 | Human | 10479 | Details Get a Quote |
| SLC9A6 Knockout A-549 Cell Line | EDJ-KQ31857 | Human | 10479 | Details Get a Quote |
| SLC9A6 Knockout HCT 116 Cell Line | EDJ-KQ31858 | Human | 10479 | Details Get a Quote |
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