Table 1

Clinical manifestations and electrophysiological studies of the families with gap junction protein β 1 (GJB1) mutations

			Clinical manifestations						Electrophysiology
Family	Mutation	Patient	Age at onset (years)	Sex/age (years)	Muscle wasting (upper/lower)	Sensory disturbance	Tendon reflex	CNS involvement	Ulnar MCV (m/s)/DML (ms)	Ulnar CMAP (mV)	Median SAP	Sural SAP
±, minimal; +, mild; ++, moderate; +++, severe; AJ, ankle jerks; CMAP, compound motor action potentials; CNS, central nervous system; D, distal; DML, distal motor latency; F, female; Fs, frame shift; M, male; MCV, motor conduction velocity; MRI, magnetic resonance image; P, proximal; SAP, sensory action potential; T2WI, T2 weighted image. *Index case.
1	W24C	1	15	F/30	D>P, +/++	Large fibre, mild	Hyporeflexia	Extensor plantar response
		2	11	F/28		Large fibre, mild	Absent AJ		53/2.7	8.0	3.5	Absent
		3	12*	M/66	D>>P, +++/+++	Both, severe	Areflexia		24/3.6	0.1	Absent
2	T55R	4	16*	M/71	D>>P, ++/+++	Both, moderate	Areflexia	Deafness and abnormal auditory brainstem potentials	33/4.9	2.5	Absent
3	E109Stop	5	25	F/33	D>P, +/++	Large fibre, mild	Areflexia	Brain MRI: high signal in the cerebral hemisphere and right mid brain in T2WI	49/3.8	0.72
		6	4*	M/12	D>P, +/++	No	Areflexia		37/3.4	1.2
		7	15 months	M/5	D>P, ±/+	No	Areflexia		49/2.3	2.4		16.1 (right medial plantar)
4	V125D	8	9*	M/16	D>>P, ++/+++	Large fibre, mild	Hyporeflexia, absent AJ		37/4.5	3.5	Absent	Absent
5	F153S	9	9*	M/12	D>P, ±/+	No	Normal, brisk AJ		51/2.9	12.8	11.3 (right radial)	Absent
		10		F/42	Asymptomatic		Hyporeflexia		55/2.6	15.0	Absent
		11	12	M/52	D>>P, ++/+++	Both, moderate			44.7/3.2	6.8	Absent
6	T191Fs	12	16*	M/54	D>>P, ++/+++	Large fibre, severe, small fibre, moderate	Areflexia	Deafness and extensor plantar response	33/4.6	1.7	Absent	Absent