T118M Variant of PMP22 Gene Presents with Painful Peripheral Neuropathy and Varying Charcot-Marie-Tooth Features: A Case Series and Review of the Literature

Table 1

Electrophysiological studies of the three cases. Amp: amplitude (μV) and Vel: velocity (m/s). NR: no response. Bold numbers indicate abnormal values.

Response	Nerve	Sites		Case 1	Case 2	Case 3
Sensory response			Genotype (T118M)	+/-	+/-	+/-
			Age	64	73	56
	Left median	Wrist	Amp	-	38.5	-
			Vel	-	53	-
	Left ulnar	Wrist	Amp	-	6.1	-
			Vel	-	43	-
	Left radial	Wrist	Amp	-	27.8	-
			Vel	-	53	-
	Left sural	Calf	Amp	NR	6.1	7
			Vel	NR	39	52
	Right sural	Calf	Amp	NR	7.4	10
			Vel	NR	46	46
	Left superficial peroneal nerve	Calf	Amp	NR		-
			Vel	NR		-
	Right superficial peroneal nerve	Calf	Amp	NR	-	-
			Vel	NR	-	-
Motor response	Left median nerve	Wrist	Amp	-	11.4	-
		Elbow	Amp	-	10.7	-
			Vel	-	56	-
	Left ulnar	Wrist	Amp	-	14.6	-
		Below elbow	Amp	-	13.4	-
			Vel	-	62	-
		Above elbow	Amp	-	12.2	-
			Vel	-	56	-
	Left peroneal	Ankle	Amp	2.8	5.5	5.9
		Fibular head	Amp	1.6	4.7	5.4
			Vel	33	39	43
		Popliteal fossa	Amp	1.6	4.7	5.2
			Vel	32	48	41
	Left tibial	Ankle	Amp	0.8	7.9	7.2
		Popliteal fossa	Amp	0.3	4.2	6.8
			Vel	33	47	38
	Right tibial	Ankle	Amp	0.9	-	14.7
		Popliteal fossa	Amp	0.4	-	10.2
			Vel	35	-	41
	Right peroneal	Ankle	Amp	4.5	-	10.4
		Fibular head	Amp	3	-	8.4
			Vel	36	-	46
		Popliteal fossa	Amp	2.9	-	7.9
			Vel	36	-	46