[Identification of families with increased risk of Down's syndrome caused by translocation of chromosome 9].

Between 1976 and 1985 in the Genetic Out-patient Department Down's syndrome was found in 260 children. In 235 children it was a result of numerical aberration, in 15 children it was a result of structural aberration (unbalanced translocation in 21 chromosome)--in 7 children t(21q21q), in 6 children t(14q21q), in 2 children t(21q22q). In 3 children translocation was transmitted by one of the parents. The performed cytogenetic examination have allowed to find out the translocation carriers in these families. So there was a possibility to identify a whole series of families with an increased risk of Down's syndrome even before the birth of child with Down's syndrome. Concerned families were informed about the possibilities of prenatal diagnosis.