Table 1.
Gene location and distribution of Na channels α subunits in subpopulations of DRG sensory neurons.
| Channel | Gene | Human chromosome location | TTX sensitivity | Expression in DRG subpopulations* | Expression levels |
|---|---|---|---|---|---|
| Nav1.1 | SCN1A | 2q2a | Sensitive | Large myelinated | ++ |
| Nav1.2 | SCN2A | 2q23–24 | Sensitive | Large myelinated/small unmyelinated | + |
| Nav1.3 | SCN3A | 2q24 | Sensitive | Not present | Increased after nerve injury |
| Nav1.4 | SCN4A | 17q23–25 | Sensitive | Not present | − |
| Nav1.5 | SCN5A | 3p21 | Resistant | Not present | − |
| Nav1.6 | SCN8A | 12q13 | Sensitive | Large myelinated | +++ |
| Nav1.7 | SCN9A | 2q24 | Sensitive | Large myelinated/small unmyelinated | +++ |
| Nav1.8 | SCN10A | 3p22–24 | Resistant | Small unmyelinated/some large | +++ |
| Nav1.9 | SCN11A | 3p21–24 | Resistant | Small unmyelinated | +++ |
*Small- (<25 μm) and Large-diameter (>30 μm) DRG neurons. State of myelination determined by overlapping expression of peripherin, NF200 and Necl-1.
+,++,+++: different levels of expression.