Autosomal recessive axonal neuropathy with neuromyotonia in a paediatric patient - a case based review

Autosomal recessive axonal neuropathy with neuromyotonia (ARAN-NM) is a distinct clinical and genetic entity within the hereditary peripheral neuropathies (HPN), caused by recessive loss-of-function mutations in the histidine triad nucleotide binding protein 1 (HINT1) gene.

We report the case of a 13-year-old girl presenting with gait impairment and progressive motor weakness starting at the age of 6, with delayed muscle relaxation after a strong voluntary contraction, which developed later in the course. Electrophysiological studies showed axonal motor polyneuropathy and neuromyotonic discharges. Molecular analysis revealed a homozygous, pathogenic variant, c.110G > C (p.Arg37Pro) in HINT1.

This case emphasises the elusive nature of ARAN-NM in children, whose clinical presentation is not distinctly characteristic at onset.