Clinical and PRRT2 gene variants analysis of three families with benign familial infantile epilepsy / 中华神经科杂志

Objective:To investigate the clinical and gene variant characteristics of benign familial infantile epilepsy in generations of three families.Methods:The clinical data of the three benign familial infantile epilepsy patients with PRRT2 gene variant who were diagnosed and their family members were collected from Children′s Hospital Affiliated to Zhengzhou University between 2018 and 2019. All coding exons from the patients and their parents were screened by targeted next-generation sequencing, and detected variants were verified by Sanger sequencing.Results:In all the patients, a cluster of seizures was observed before one year old,but interictal clinical conditions were normal. The electroencephalograms were all normal in interictal stage. The father of proband 1 presented with convulsion onset at the age of eight months and showed remission before one year old. The grandpa, mother and uncle of proband 2 also presented with convulsion onset in their babyhood of life and showed remission before one year old. The mother of proband 3 presented with convulsion onset in their babyhood of life and showed remission before three years old. Proband 1 carried heterozygous c.937G>C variant in the PRRT2 gene which is inherited from his father. Proband 2 carried c.1075_c.1076insC variant inherited from his mother. A deletion of PRRT2 gene exon 2 was detected in both of proband 3 and her mother. The three variants had not been reported in the Human Gene Mutation Database.Conclusions:Benign familial infantile epilepsy is a kind of inherited epilepsy characterized by early onset of seizure in babyhood with better prognosis, a cluster of focal seizures with or without secondary generalization, and cessation of seizure mostly before two or three years of age. The variants c.937G>C, c.1075_c.1076insC and the deletion of exon 2 in the PRRT2 gene have enriched the gene variant spectrum of benign familial infantile epilepsy.

Identification of two novel PRRT2 gene variants in two children with paroxysmal kinesigenic dyskinesia / 中华医学遗传学杂志

Objective@#To analyze variants of PRRT2 gene in two children with paroxysmal kinesigenic dyskinesia.@*Methods@#Genomic DNA of the two children and their parents was extracted from peripheral venous blood samples. All exons and their flanking regions of the PRRT2 gene were subjected to PCR and Sanger sequencing.@*Results@#The two children were found to respectively harbor a c. 282dupA and a c. 715_716dupCC variant in exon 2 of the PRRT2 gene, which were both inherited from their mothers. Pooling together their frequencies in general population, genetic models, related literature and impact on protein function, the two novel variants were both predicted to be pathogenic.@*Conclusion@#The c. 282dupA and c. 715_716dupCC variants probably underlie the disease in the two children.

The Clinical and prognosis of PRRT2 gene-related paroxysmal disorders (Report of 1 case) / 临床神经病学杂志

Objective To investigate the clinical features and prognosis of PRRT2-related paroxysmal disorders. Methods Retrospected clinical data of one cases of benign infantile epilepsy diagnosed by gene diagnosis. Results The clinical manifestations of this Children were recurrent convulsions,cluster seizures,and no obvious abnormalities in physical examination. Genetic examination showed mutation of PRRT2 frameshift. Her mother had a history of paroxysmal motor-induced dyskinesia,and her uncle and cousin had a history of convulsions when they were young. The patient did not convulse after oral oxcarbazepine. Conclusions PRRT2 gene-related paroxysmal diseases are characterized by self-limited infantile epilepsy and paroxysmal motor-induced dyskinesia. Genetic diagnosis is needed for definitive diagnosis.The main treatment of this disease is to control epilepsy,and the prognosis is good.

Study of Pathogenic gene spectrum in benign familial infantile epilepsy / 中华实用儿科临床杂志

Objective To investigate the gene mutations in benign familial infantile epilepsy(BFIE)in Chi-na. Methods Data of all BFIE probands and their family members were collected from Peking University First Hospital and other three hospitals between October 2006 and June 2017. Clinical phenotypes of affected members were analyzed. Genomic DNA was extracted from peripheral blood samples with standard protocol. Mutations in PRRT2 were screened using Sanger sequencing. For families that PRRT2 mutations were not detected by Sanger sequencing,candidate gene mutations were further screened by next - generation sequencing. Results A total of 71 families including 227 affected members were collected. Genetic testing led to the identification of gene mutations in 52 families (52 / 71,73. 2％). Forty - three families had PRRT2 mutations (43 / 71,60. 6％),including 40 families with frameshift mutations(hotspot mutations c. 649_650insC and c. 649delC were detected in 29 families and 6 families,respectively),one family with nonsense mutation,one family with a loss of a stop codon,and one family with a microdeletion of the gene. C. 560_561insT and c. 679C > T were novel PRRT2 mutations. Five families had SCN2A mutations. All SCN2A mutations were missense mutations(c. 668G > A,c. 752T > C,c. 1307T > C,c. 4835C > G,c. 1737C > G). Mutation c. 752T > C, c. 1307T > C,c. 4835C > G,and c. 1737C > G were novel mutations. Three families had KCNQ2 mutations. All KCNQ2 mutations were missense mutations(c. 775G > A,c. 237T > G,c. 1510C > T). Mutation c. 237T > G and c. 1510C > T were novel mutations. One family had a novel GABRA6 mutation c. 523G > T. In 71 BFIE families,16 families had mem-bers who showed paroxysmal kinesigenic dyskinesias(PKD)and subclassified as infantile convulsions with paroxysmal choreoathetosis syndrome(ICCA). Fifteen ICCA families were found having PRRT2 mutations (15 / 16,93. 8％). The remaining ICCA family was not detected with any pathogenic mutation. Conclusion There is high frequency of gene mutations in BFIE families. Mutations in KCNQ2,SCN2A,and PRRT2 are genetic causes of BFIE. PRRT2 is the main gene responsible for BFIE. GABRA6 mutation might be a new cause of BFIE.

A case report of paroxysmal kinesigenic dyskinesia and literature review / 临床儿科杂志

Objective To investigate the clinical features of paroxysmal kinesigenic dyskinesia (PKD) and the mutation features of its pathogenic gene proline-rich transmenbrane protein 2 (PRRT2). Method The clinical manifestations and genetic tests of one case of PKD were retrospectively analyzed, and the related literatures were reviewed. Results A 10 year and 9 month male patient was recruited. The age of dyskinesias onset was 7 year and 6 month. The descriptions of the attacks were abnormal involuntary movements which were induced by sudden voluntary movements and presented with dystonia. The frequency of the attacks was three to ifve times per day with the duration lasting ten to twenty seconds, and there is no loss of consciousness. Treatment with oxcarbazepine is effective. A heterozygous mutation in PRRT2 gene, c.649_650insC (p. 217fs224X), was found by genetic testing, and the mutation was inherited from the patient’s mother who showed no symptom of PKD. Conclusion The onset age of PKD could be in the childhood and adolescence. The attack is provoked by sudden movements and the duration time is short. Treatment with antiepileptic drug is effective. The test of PRRT2 gene may help diagnosis. Mutation c.649_650insC is the hotspot mutation of the gene.