Investigators from the Children's Hospital, Coimbra, Portugal, and centers in Belgium, report a 16-year-old girl with consanguineous parents who presented with progressive distal muscular atrophy and weakness, beginning at age 6 years. After 10 years follow-up, clinical myotonia developed and was confirmed by electrophysiologic studies. This severe chronic motor axonal neuropathy was associated with a homozygous mutation in HINT1 and with late onset neuromyotonia. Sensory impairment was discrete and also appeared late. [1]
COMMENTARY. Autosomal recessive axonal neuropathy with neuromyotonia is recently described in 50 patients from 33 families, with 8 different HINT1 mutations, in a report including the above patient and cited by the authors [2]. The disease presents in the first decade with distal muscle weakness in upper and lower limbs. Sensory impairment is mild in some and most develop action myotonia in the hands and orthopedic deformities.