Cytogenetic screening of a new-born population.

Chromosomes were analysed using banding techniques in 1830 consecutively born infants. The prevalence of chromosomal aberrations was 19.67 per 1000, which is higher than figures found in previous cytogenetic surveys using conventional staining (8.34 and 5.75 per 1000 in a Danish and a combined survey, respectively). The use of banding techniques may explain the higher rate of detection of chromosomal variants in the present study. This is illustrated by the findings of 7.10 autosomal inversions per 1000 compared to 0.13 in a combined survey, and Y chromosome inversions of 3.14 compared to 0.26 per 1000. A prevalence of 2.73 balanced reciprocal translocations per 1000 was found, involving chromosomes 1, 2, 3, 9, 11, 13, 16 and 22, which all belong to a group of ten chromosomes with the highest number of spontaneous breaks in the study of Aymé et al. (1976). Fourteen infants were found to have chromosomal mosaicism, and three of them were defined as real mosaics. With the increasing concern about the effect of environmental toxicants, it is of interest to keep a record of aberrant cells in presumably karyotypically normal newborns for possible use in future epidemiological surveys.