Table 1.
Clinical and electrophysiological features of current and reported CMT patient with SLC12A6 heterozygous variants.
| Kahle et al. (2016) | Park et al. (2019) | Shi et al. (2021) | This report | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Patient 1 | Patient 1 | Patient 2 | Patient 3 | Patient 1 | Patient 1 | Patient 2 | Patient 3 | Patient 4 | Patient 5 | Patient 6 | Patient 7 | |
| Mutation | c.2971A>G | c.620G>A | c.620G>A | c.2036A>G | c.620G>A | c.620G>A | c.865G>A | c.865G>A | c.1731_1733del | c.1731_1733del | c.1731_1733del | c.2036A>C |
| p. T991A | p.R207H | p.R207H | p.Y679C | p.R207H | p.R207H | p.E289L | p.E289L | p.F578del | p.F578del | p.F578del | p.Y679S | |
| Ethnicity | American | German | German | German | Chinesse | Japanese | Japanese | Japanese | Japanese | Japanese | Japanese | Japanese |
| Onset age | 9 month | 1–2 y.o | 1–2 y.o | 1–2 y.o | 27 y.o | 1 y.o | 11 y.o | 10 y.o | 19 y.o | 40 y.o | 39 y.o | 3 y.o |
| Exam age | 10 y.o | 11 y.o | 11 y.o | 15 y.o | 31 y.o | 8 y.o | 13 y.o | 40 y.o | 19 y.o | 52 y.o | 47 y.o | 26 y.o |
| Genotype | Sporadic | Sporadic | Sporadic | Sporadic | Sporadic | Sporadic | AD | AD | AD | AD | AD | Sporadic |
| Gender | Male | Male | Male | Female | Male | Female | Male | Female | Female | Female | Female | Female |
| Distal weakness | + | + | + | − | + | + | + | + | + | + | + | + |
| Distal atrophy | + | + | + | + | + | + | − | − | + | + | + | + |
| Distal leg MMT | 1–2 | 4− | 4+ | NA | 0 | 4 | 4 | NA | 2 | NA | 3 | 1 |
| Sensory disturbance | − | − | + | + | + | + | + | NA | + | + | − | + |
| DTR | Absent | Decrease | Absent | Brisk | Absent | Absent | Decrease | Absent | Absent | n.a | Absent | Absent |
| Cognitive impaiment | − | − | − | NA | − | − | Poor school record | − | IQ71 | − | − | IQ46 |
| Other symptom | − | Hemolytic anemia | No seizure EEG; burst of genernlised spike and polyspike and wave | Spasticity celiac disease short stature migrane bladder and bowel incontinence | CK427 | Low vision | CK533 | − | CK1162 | − | − | Epilepsy hemolytic anemia |
| Median CMAP (mV) | 0.2 | 1.2 | 3.7–7.3 | Normal | 1.6/5.4 | n.a | 6.2 | 2.5 | 5.65 | 5.5 | 5.4 | 0.6/0.2 |
| Median MNCV (m/sec) | 31 | 33 | 32–35 | Normal | 41/41.8 | 31/42 | 40.3 | 38 | 39.3 | 53 | 54.5 | 33.6/25.1 |
| Median SNAP (μV) | 9 | 3.5 | NE | Normal | 1.0/1.37 | n.a | NE | NE | 1.3 | 4 | NE | 2.0/1.0 |
| Median SCV (m/sec) | 44 | 21 | NE | Normal | 32.4/30.7 | n.a | NE | NE | 38.6 | 39 | NE | 40.9/40.0 |
| Tibial CMAP (mV) | NA | 3.5 | NE | 33–40 | 0.07/0.31 | n.a | 2.3 | 0.3 | 0.13 | 2.1 | 0.13 | 0.14/0.05 |
| Tibial MNCV (m/sec) | NA | 23 | NE | 1–1.9 | NA | 21/24 | 39.8 | 29 | 41.6 | 46 | 69.2 | 13.8/21.1 |
| Sural SNAP (μV) | 8 | NE | NE | NE | NE | n.a | NE | NE | 0.3 | NE | NE | 1.0/2.0 |
| Sural SCV (m/sec) | 27 | NE | NE | NE | NE | n.a | NE | NE | 25.2 | NE | NE | 34.1/32.3 |
| Brain MRI | Normal | Normal | Normal | Normal | Normal | NA | NA | NA | NA | NA | NA | brain atrophy |
MMT, manual muscle test; DTR, deep tendon reflex; NA, not available; AD, autosomal dominant; CK, Creatine kinase (U/L); IQ, intelligence quotient; MNCV, Motor nerve conduction velocity; CMAP, Compound motor action potential; SCV, sensory nerve conduction velocity, SNAP, sensory nerve action potential; NE, not evoked; Normal range, median CMAP >3.1 mV; median MNCV >49.6 m/sec; median SNAP >7.0 μV; median SCV >47.2 m/sec; tibial CMAP >4.4 mV; tibial MNCV >41.7 m/sec; sural SNAP >5.0 μV; sural SCV >40.8 m/sec.