ABSTRACT
Objective To investigate the gene mutations in benign familial neonatal epilepsy(BFNE) in China.Methods Data of all BFNE probands and their family members were collected from Peking University First Hospital from January 2012 to December 2013.Clinical phenotypes of affected members were analyzed.Genomic DNA was extracted from peripheral blood samples with standard protocol.Mutations in candidate genes mutations were further screened by next-generation sequencing.Results A total of 4 families were collected,from which there were 10 affected members,6 males and 4 females.The age of epilepsy onset was from 1 day to 4 days after birth.The age of last seizure was from 3 days to 3 years and 10 months old.The age of last follow-up was from 4 years and 3 months old to 37 years old.All affected members had normal development.Genetic testing identified KCNQ2 mutations in 3 families (75％,3/4 cases).Two families had missense KCNQ2 mutations (c.1048A ＞ C/p.N350H and c.242T ＞ C/ p.L81P).One family had nonsense KCNQ2 mutation(c.2506G ＞ T/p.E836X).The other 3 KCNQ2 mutations were novel.The remaining BFNE family was not detected with any pathogenic mutation.The age of inital seizure onset of the proband was 1 day after birth.The seizures got controlled at 3 months old.However,this proband had another 2 afebrile seizures during sleep at 3 years and 10 months old.Electroenlephalography monitoring showed focal central temporal spikes.It is speculated that the seizures had evolved into benign epilepsy of childhood with central temporal spikes.Conclusions Mutations in KCNQ2 are major genetic causes in Chinese families with BFNE.KCNQ2 mutation c.1048A ＞ C/p.N350H,c.242T ＞ C/p.L81P,and c.2506G ＞ T/p.E836X are novel mutations.Identification of underlying gene mutation can be helpful for clinical diagnosis and judgment of the prognosis.
ABSTRACT
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.