Table 1

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

Clinical manifestationsElectrophysiology
FamilyMutationPatientAge at onset (years)Sex/age (years)Muscle wasting (upper/lower)Sensory disturbanceTendon reflexCNS involvementUlnar MCV (m/s)/DML (ms)Ulnar CMAP (mV)Median SAPSural 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.
1W24C115F/30D>P, +/++Large fibre, mildHyporeflexiaExtensor plantar response
211F/28Large fibre, mildAbsent AJ53/
312*M/66D>>P, +++/+++Both, severeAreflexia24/3.60.1Absent
2T55R416*M/71D>>P, ++/+++Both, moderateAreflexiaDeafness and abnormal auditory brainstem potentials33/4.92.5Absent
3E109Stop525F/33D>P, +/++Large fibre, mildAreflexiaBrain MRI: high signal in the cerebral hemisphere and right mid brain in T2WI49/3.80.72
64*M/12D>P, +/++NoAreflexia37/3.41.2
715 monthsM/5D>P, ±/+NoAreflexia49/2.32.416.1 (right medial plantar)
4V125D89*M/16D>>P, ++/+++Large fibre, mildHyporeflexia, absent AJ37/4.53.5AbsentAbsent
5F153S99*M/12D>P, ±/+NoNormal, brisk AJ51/2.912.811.3 (right radial)Absent
1112M/52D>>P, ++/+++Both, moderate44.7/3.26.8Absent
6T191Fs1216*M/54D>>P, ++/+++Large fibre, severe, small fibre, moderateAreflexiaDeafness and extensor plantar response33/4.61.7AbsentAbsent