Novel compound heterozygous TBC1D24 mutations in a boy with infantile focal myoclonic epilepsy and literature review / 中华儿科杂志

ABSTRACT

Objective@#To investigate the clinical features and genetic characteristics of patients with TBC1D24 gene mutations.@*Method@#The clinical data of a patient with novel TBC1D24 compound heterozygous mutations from Children′s Hospital of Fudan University were collected, the related literature was searched from China National Knowledge Infrastructure, Wanfang Data Knowledge Service Platform, National Center from Biotechnology Information and Pubmed (up to April 2016) by using search terms "TBC1D24" "epilepsy" . The clinical features, electroencephalogram (EEG) and prognosis of the patients with TBC1D24 gene mutations were studied.@*Result@#The patient was a boy with non-consanguineous healthy parents.He had an acute episode of focal continuous myoclonus lasting a few hours with consciousness preserved at the age of 3 months.Myoclonic jerks alternatively affected the eyelids, either the right or left limbs, sometimes triggered by fever or fatigue.The frequency was once 3-7 days.At the age of 6 months he was found to have myoclonus seizures with onset from a unilateral eyes lid and limb lasting 10 more minutes and subsequently affected four extremities or the trunk.They occurred once 3-4 months with perserved consciousness and lasted from several hours to up to ten more hours.They mostly disappeared during sleep.He had ataxia and mild mental retarding.Paroxysmal anomalies were not found on ictal traces.A novel compound heterozygous mutation of TBC1D24 gene, c. 730G>A, p.A244T and c. 1571G>C, p.R524P were found in the patient.Further study showed that c. 730G>A mutation was inherited from his father and c. 1571G>C from his mother. These two were not reported in public databases and predicted deleterious by Mutation Taster and polyphen-2.Literature relevant to TBC1D24 published all around the world was reviewed, no Chinese cases with TBC1D24 gene mutations had been reported. The total of 24 cases including the present case with TBC1D24 gene mutation were reported.Among them, 11 cases had compound heterozygous mutations and 13 cases had homozygous mutations.Ten mutations were identified, including 1 termination mutation, 1 frameshift mutation and 8 missense mutations.@*Conclusion@#TBC1D24 gene mutational analysis should be performed on patients with early-onset focal continuous myoclonus, if the etiology was unclear.