Table 4
Phenotypic similarities and differences (in bold) between CSNBX genotypes
| Feature | NYX gene mutations | CACNA1F mutation |
|---|---|---|
| Clinical examination | ||
| Visual acuity | Variably reduced (range 6/9–6/60) | Variably reduced (range 6/9–6/60) |
| Nystagmus | 72% | 83% |
| Strabismus | 86%, esotropia in majority | 100%, esotropia in all |
| Myopia | 100% (mean −7.25DS) | 100% (mean −8.0DS) |
| Psychophysics | ||
| Scotopic perimetry | Rod threshold elevation (mean 3.5 log units) | Rod threshold elevation (mean 2.0 log units) |
| Cone threshold elevation (mean 2.0 log units) | Cone threshold elevation (mean 1.9 log units) | |
| Dark adaptometry | Rod-cone break detected | Rod-cone break detected |
| Normal kinetics | Normal kinetics | |
| Electrophysiology | ||
| Scotopic b-wave response | Subnormal | Subnormal |
| Scotopic oscillatory potential (OP1 or 2) | Absent | Subnormal |
| 30 Hz flicker | Sawtooth waveform | Biphasic waveform |
| Normal amplitude | Subnormal amplitude | |
| ON response | Subnormal | Subnormal |
| OFF response | Normal | Subnormal |
