Objective: Myoclonus, ataxia, tremor and dystonia have been described in some patients with TBC1D2B gene mutation. In this paper we present a patient with progressive limb myoclonus and gait ataxia in novel TBC1D2B gene mutation.

Background: TBC1D2B plays a role of endosomal trafficking in cells. It’s gen mutations are associated neurodevelopmental disorder with seizures and gingival overgrowth in childhood.

Method: A girl patient, whose growth development was normal until the age of 10. Then, started to have gait disturbance and myoclonus in arms. Cognitive impairment and epileptic seizures were observed to increase over the years. Four years later, she was unable to walk without support. Diffuse myoclonic jerks was observed along with speech disorder and difficulty in swallowing.

Results: In the genetic examination, a novel heterozygous mutation was detected in the TBC1D2B gene (c.360+1G>T, splice donor variant).

Conclusion: TBC1D2B gene mutation should be considered in the etiology of patients with progressive myoclonus and ataxia in childhood.

References: 1- Harms FL et al. Loss of TBC1D2B causes a progressive neurological disorder with gingival overgrowth. Eur J Hum Genet. 2024
2- Correia-Costa GR et al. Biallelic frameshift variant in the TBC1D2B gene in two siblings with progressive gingival overgrowth, fibrous dysplasia of face, and mental deterioration. Clin Genet. 2022
3- Harms FL et al. Biallelic loss-of-function variants in TBC1D2B cause a neurodevelopmental disorder with seizures and gingival overgrowth. Hum Mutat. 2020

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MDS Abstracts - https://www.mdsabstracts.org/abstract/childhood-onset-progressive-myoclonus-and-ataxia-in-a-patient-with-novel-tbc1d2b-gene-mutation/