OBJECTIVE: Benign familial infantile convulsions (BFIC) is a form of idiopathic 
epileptic syndrome characterized by onset of afebrile seizures between 3 and 12 
months of life, Spontaneous remission after several weeks or months, and 
autosomal dominant mode of inheritance. Previous linkage analysis in western 
countries defined three susceptible loci on chromosomes 19q12.0-13.1, 16p12-q12, 
and 2q23-31, but studies performed in several Chinese families with BFIC got 
negative results of these previously reported loci. The authors investigated the 
relation of voltage-gated potassium channel gene KCNQ2 to BFIC in a Chinese 
family and thus to understand the molecular pathogenesis of BFIC.
METHODS: A four-generation Chinese BFIC family was investigated. All the 
affected 17 members had similar pattern of seizures starting from 2 to 6 months 
of age. In 15 of them, the seizures disappeared spontaneously within the first 
year of life. The phenotype extended beyond infancy only in two patients. Blood 
sample was collected from the 41 family members and 75 unassociated normal 
individuals. Polymerase chain reaction (PCR)-DNA direct sequencing was performed 
to screen all exons and their flanking introns of KCNQ2 gene for mutation 
analysis. Polymerase chain reaction-single strand conformation polymorphism 
(PCR-SSCP) was used to ascertain the co-segregation of genotype and phenotype 
and to exclude polymorphism.
RESULTS: PCR amplification and subsequent direct sequencing of KCNQ2 from the 
DNA of proband revealed a heterozygous guanine to thymine nucleotide exchange 
(G812T) in exon 5, leading to the substitution of glycine by valine at amino 
acid position 271 (G271V) of the predicted protein. The same mutation with a 
comparable localization has been previously described for KCNQ3 in benign 
familial neonatal convulsions (BFNC). The glycine at this position (G271) is 
located in pore region of KCNQ2 protein and is evolutionarily highly conserved. 
The same SSCP variant as that of the proband was shown in the rest of the 
affected members of this family but not in the unaffected members enrolled in 
the study of this family and all the 75 unrelated normal individuals.
CONCLUSION: Previously reported mutations of KCNQ2 were mainly identified in 
BFNC family in which at least one individual had an onset of seizures during the 
first week of life, a hallmark of the BFNC disorder. The results of the present 
study suggest the possibility that KCNQ2 mutation exist in patients with BFIC 
diagnosis. G812T of KCNQ2 gene is a novel mutation found in BFIC and functional 
expression of KCNQ2 G812T is required for understanding the mechanism of BFIC 
and other idiopathic epilepsy.