Autosomal recessive axonal neuropathy with neuromyotonia in a Tibetan family caused by HINT1 gene variation and literature review / 中华实用儿科临床杂志

ABSTRACT

Objective:To summarize the characteristics of autosomal recessive axonal neuropathy with neuromyotonia (ARAN-NM) caused by HINT1 gene mutation. Methods:Retrospective case summary.Clinical data of 2 Tibetan siblings diagnosed with ARAN-NM in the Department of Pediatrics of Peking University First Hospital in August 2023 were retrospectively analyzed.A review of literature reporting relevant Chinese patients was conducted.Results:The proband and her elder brother were aged 13 and 19, respectively.Both developed abnormal gait at the age of 11, followed by varus, claudication, and weak thumb strength.The proband also had neuromyotonia.Physical examinations showed that the proband and her elder brother had decreased muscle strength of the extremities, mainly in the thumbs and distal ends of lower limbs.The distal muscles of the proband′s lower extremities and the muscles of both hands of the proband′s elder brother were atrophied.Both feet showed talipes equinovarus in the proband and her elder brother.The proband′s electromyography (EMG) showed peripheral nerve injuries (motor and sensory axonal involvement, especially in distal ends) and myotonic potentials.The trio-whole exon sequencing detected homozygous pathogenic variation in HINT1 gene in both the proband and her elder brother, who were diagnosed as ARAN-NM based on c. 169A>G (p.K57E). After the Carbamazepine treatment, the proband′s neuromyotonia, numbness and weakness were relieved.Both the proband and her elder brother underwent orthopaedic surgery and rehabilitation.Their foot deformities and gait were significantly improved.Two Chinese literatures (2 patients) and four English literatures (8 patients) were retrieved.Including the proband and her elder brother in this study, there were 12 ARAN-NM patients, 10 of whom had clinical data.The ages of onset and diagnosis were 2-16 (1 case unknown) and 13-33 years old, respectively.Myasthenia was present in 9 patients, especially in distal ends.Eight patients were complicated with neuromyotonia, nine patients with muscle atrophy, seven patients with foot deformity, and two patients with sensory disturbance.Creatine kinase(CK) was elevated in all 9 patients tested or CK.EMG showed neurogenic injuries in all patients and neuromyotonia discharge in six patients.Three patients were treated with Carbamazepine, and some symptoms were relieved.Missense/nonsense mutations were found in the 12 patients, and the high-frequency variation was c. 112T>C (p.C38R). Conclusions:ARAN-NM is a rare autosomal recessive neuromuscular disease caused by HINT1 gene mutation.There is no ethnic difference in clinical manifestations, mainly distal limb weakness with neuromyotonia.Carbamazepine can alleviate some symptoms, and orthopaedic surgery can improve foot deformity and gait.