Hereditary axonal neuropathy with myoclonus: novel ATL3 mutation phenotype

Background. Hereditary motor-sensory neuropathy (HMSN), also known as Charcot-Marie-Tooth (CMT), is a disorder characterized by chronic sensory and motor polyneuropathy, resulting in distal motor neuropathy. HMSN is genetically heterogeneous, with over 90 pathogenic genes identified. Myoclonus is an unusual association of HMSN. Case report. A 23-year-old female presented with myoclonic jerks since the age of 5, progressing to involve all four limbs. A few years later, she developed insidious progressive distal predominant weakness in all four limbs. By age 15, she required a wheelchair. Examination revealed hypotonia, diminished reflexes, and distal muscle weakness. Genetic analysis identified a heterozygous missense variant in exon 9 of the ATL3 gene. Her brother exhibited similar symptoms and had the same mutation. Conclusions. ATL3 mutations are associated with hereditary sensory neuropathy type IF. This case highlights a novel phenotypic presentation, including myoclonus and short stature, not previously described with ATL3 mutations. Early diagnosis and genetic counseling are crucial for managing HMSN.