PP09.9 – 2907: Is it easy to recognize HINT1 neuropathy

Objective Autosomal recessive axonal neuropathy with neuromyotonia and mutation in HINT1 gene form a new disease entity among the myotonic syndromes (Zimon M et al, 2012) and presents one of the most frequent genotype within CMT2/HMN (Lassuthova et al, 2014). Purpose: To present clinical and neurophysiology problems in diagnostic procedure of HINT1 neuropathy. Methods Conventional ENMG technique was applied (Premier, Medelec apparatus) according to standard protocol. Molecular genetics studies were done in VIB Department of Molecular Genetics, Antwerpen and in Neurogenetic lab. in Belgrade. Results 18 HINT1 (founder R37P) patients from 11 families expressed unique CMT phenotype, sometimes with clinically hardly recognizable myotonia. ENMG was typical for axonal neuropathies with neuromyotonia (NT), but in some patients NT was detectable only in non-distal limb muscles. Multigeneration inheritance was found in two families. Conclusion Our patients expressed founder mutation in HINT1 gene and possible pseudodominant transmission which could stimulate AD-CMT2 diagnosis. ENG is enough for differentiating axonal from demyelinating neuropathies, but needle EMG for distal and proximal muscles is necessary for detecting NT.