Since 1963 intermittent reports have appeared which indicated that deletion of a D chromosome, with or without ring formation, could be associated with various congenital malformations (Bain and Gauld, 1963; Lele, Penrose, and Stallard, 1963; Thompson and Lyons, 1965; Jacobsen, 1966; van Kempen, 1966; Bloom, Gerald, and Reisman, 1967, Gerald et al, 1967; Juberg et al, 1969; Laurent et al, 1967;...
