A CYTOGENETIC SURVEY OF 14,835 CONSECUTIVE LIVEBORNS

The results of chromosome studies on cultured umbilical cord blood lymphocytes from a consecutive series of 14,835 liveborn infants (7,608 males and 7,227 females) are described. Ninety-three infants (6.27 per 1,000) had a major chromosome abnormality. Of these, thirty-one infants (2.09 per 1,000) had sex chromosome abnormalities. Seven male infants had a 47,XXY karyotype, five had a 47,XYY karyotype, and three were mosaics. One male had a ring Y chromosome in all cells examined. A pericentric inversion of the Y chromosome was found in one case. Seven female infants had a 47,XXX karyotype, one had a 45,X karyotype and six were mosaics. Sixty-two infants (4.18 per 1,000) had autosomal abnormalities. There were twenty-one infants with trisomy 21 including one mosaic, six infants with trisomy 18, and two infants with trisomy 13 of a Robertsonian translocation type. Three infants had an unbalanced derivative chromosome resulting from a parental reciprocal translocation. Two infants with a partial monosomy of chromosome 13 were detected. There were four infants carrying an additional small marker chromosome. Twenty-four infants (1.62 per 1,000) had a balanced structural rearrangement of the autosomes; eleven with a Robertsonian translocation, eleven with a reciprocal translocation, and two with a pericentric inversion. The incidence of each type of major chromosome abnormality in this study was quite similar to that obtained from previous newborn surveys.