Abstract: Objective To investigate the clinical manifestations and pedigree of a child with familial infantile myoclonic epilepsy caused by TBC1D24 gene mutation，and the relevant literatures were reviewed. Objective This study collected a case of familial myoclonic epilepsy with development delay caused by TBC1D24 gene mutation which was admitted to the Department of Neurology，Wuhan Children′s Hospital，reviewed literatures，summarized clinical manifestations and the update of diagnosis and treatment. Results The propositus，female，six years and nine months old，was hospitalized in July 2018 due to ″ intermittent convulsions for more than six years″ . The child had convulsions when she was two months old. The convulsions were in the form of paroxysmal blue and purple of the complexion and the end of her limbs. She had seizures every day. When she was three years old，the convulsions were in the form of myoclonic seizures. The seizures occurred once in two or three months. Many kinds of antiepileptic drugs were used but they could not control well，the patient had severe development delay. No positive signs were found in the physical examination. The auxiliary examination： the MRI of the head was normal， and the electroencephalogram showed EPC（epilepsia partialis continua ）. The younger brother of the propositus，male，three years and six months old. Convulsions were mainly manifested as involuntary shaking of both upper limbs and face，remission after sleep，no treatment with antiepileptic drugs，and mild mental disorders. One gene mutation was found in propositus，TBC1D24 was the compound heterozygous missense mutation（c.1207（exon 6）G> T ，p.v403l），（c.1499（exon 7）C> T，P.A500V）. The former was inherited from father，the latter from mother，and the younger brother of the proband had the same TBC1D24 site mutation. Conclusion TBC1D24 is the main pathogenic gene of the propositus and her younger brother. It is suggested to screen TBC1D24 gene for refractory myoclonic epilepsy with severe mental disorders.

Key words: epilepsy, familial infantile myoclonus, TBC1D24, development delay