to the Symposium.- Clinical Aspects of Down’s Syndrome from Infancy to Adult Life.- Down’s Syndrome: Problems of Immunodeficiency.- Dermatoglyphie Peculiarities in Down’s Syndrome Detection of Mosaicism and Balanced Translocation Carriers.- Pathology of Trisomy 21.- Down’s Syndrome and the Family.- Asking for a Prenatal Diagnosis After the Birth of a Child with Down’s Syndrome.- Vingt Ans Après.- Nondisjunction.- Experiments on Chiasmata and Nondisjunction in Mice.- Gene Mapping and Chromosome 21: History and Methodology.- Functional Implications of Gene Dosage Effects in Trisomy 21.- Structural Variation of Chromosome 21 and Symptoms of Down’s Syndrome.- Prenatal Losses of Trisomy 21.- Incidence of Down’s Syndrome in Sweden During the years 1968 – 1977.- Epidemiology of Trisomy 21 Population, Peri- and Antenatal Data.- Abstracts of the Poster Presentations.- Author Index of Abstracts.