Moscow city. Meeting room of the XIV International Congress of Geneticists in the Kremlin Palace of Congresses. Delegates are speaking. Interview, press conference of the French geneticist G. Lejeune. A geneticist at the Institute of Medical Genetics of the USSR Academy of Medical Sciences talks to a woman who has a deviation in the chromosome arrangement, which led to the birth of a child with Down's disease. Examination of a pregnant woman at the Institute of Obstetrics and Gynecology of the USSR Academy of Medical Sciences.