TY - JOUR T1 - <em>GJB1</em> gene mutations in suspected inflammatory demyelinating neuropathies not responding to treatment JF - Journal of Neurology, Neurosurgery &amp; Psychiatry JO - J Neurol Neurosurg Psychiatry SP - 699 LP - 700 DO - 10.1136/jnnp.2008.150557 VL - 80 IS - 6 AU - A W Michell AU - M Laura AU - J Blake AU - M P Lunn AU - A Cox AU - V S Gibbons AU - M B Davis AU - N W Wood AU - H Manji AU - H Houlden AU - N M F Murray AU - M M Reilly Y1 - 2009/06/01 UR - http://jnnp.bmj.com/content/80/6/699.abstract N2 - It is generally accepted that while inflammatory demyelinating neuropathies often cause patchy demyelination resulting in conduction block, temporal dispersion and variation in conduction velocities, demyelinating hereditary neuropathies such as Charcot–Marie–Tooth (CMT) disease type 1A are usually characterised by homogeneous slow conduction.X-linked CMT is caused by mutations in the gap junction beta 1 (GJB1) gene encoding connexin 32, a gap junction protein, resulting in intermediate conduction velocities. At our institution, mean median nerve conduction velocity in men with GJB1 mutations is 33.2 ± 7.5 m/s (n = 13) and 47.7 ± 7.0 m/s in women (n = 8), similar to other recent series.1 2 There is increasing evidence that nerve conduction is not always homogeneous in GJB1 associated CMT.1–4 Here we present three cases in which the neurophysiology suggested an inflammatory demyelinating neuropathy, but who failed to respond to treatment and were subsequently found to have mutations in GJB1.Case No 1A 23-year-old man presented with parasthesia affecting both feet that progressed to mild hand parasthesia and weakness over 6 months. Although slightly clumsy, he had been good at sport as a teenager. He had minimal wasting but normal power in his hands, he was areflexic and had reduced vibration and pinprick distally. CSF was acellular, with a raised protein of 0.78 g/l. His initial nerve conduction studies (NCS) (done elsewhere) suggested chronic … ER -