Chromosome survey of newborn infants in Tokyo: follow-up study for XYY.

In order to ascertain the frequency of chromosome aberrations among newborn infants in Japan, a chromosome survey of a large number of newborn infants is in progress. A series of 10,270 consecutive newborn babies, 5,341 male and 4,929 female, have been screened for clinical manifestations of autosomal aberrations and for sex-chromatin and sex-chromosome aberrations. Chromosome studies were carried out on 185 infants with suspected chromosome aberrations. Of these, 23 had abnormal karyotypes, including 2 males with a 47,XXY complement, 1 female with 45,X complement, 3 males with a 47,XYY complement, 2 with trisomy 13 syndrome, 3 with trisomy 18 (including one mosaicism), 10 with Down syndrome (including 1 mosaicism), 1 with B5p partial trisomy, and 1 with Y-D translocation. Developmental studies of four XYY children and one 45,X girl are in progress.