A novel mutation of KCNQ3 (c.925T→C) in a Japanese family with benign familial neonatal convulsions

At present, only one mutation of KCNQ3, a KCNQ potassium channel gene, has been identified as a cause of benign familial neonatal convulsions type 2 (BFNC2). We found a T to C substitution (c.925TC) on one allele of affected individuals in a Japanese family with BFNC but not on 200 alleles from healthy subjects. c.925TC replaced Trp309, a conserved residue within the P-loop of the KCNQ potassium channel family that holds the channel pore open, with an Arg (W309R). We report c.925TC as the second mutation of KCNQ3 responsible for BFNC2. Ann Neurol 2000;47:822–826