Previously, MAO activity in platelets of DS individuals was found to be reduced (Benson and Southgate, 1970, Fowler et al., 1981) or unaltered (Lott et al., 1972), whereas COMT activity was higher (Gustavson et al., 1973) or unaltered (Brahe et al., 1985) in DS erythrocytes. This evidence concerns the gene COMT and Dravet syndrome.