– De novo reciprocal translocation t (3; 8) (q21, q24) truncating KCNQ3.Found in one patient with delayed verbal and social development affected by idiopathic periodic trembling.– P574S: loss-of-function significantly reduces potassium current amplitude in Xenopus laevis oocytes when co-expressed with Kv7.5 subunit but not with Kv7.2 or Kv7.4 subunits.Found in three patients affected by autism. This evidence concerns the gene KCNQ5 and autism.