A chromosome survey of 2,400 normal newborn infants

In order to ascertain the variety and frequency of chromosome abnormalities among normal individuals, a chromosome survey of a large number of newborn infants is in progress. This report describes the results obtained from an abbreviated chromosome analysis of 2,400 phenotypically normal newborn infants. Even though this method provides only a minimal estimate, 13 major chromosome abnormalities were observed. These included 4 instances of sex-chromosome aneuploidy and 9 instances of structural rearrangements. Two instances of the centric fusion type of D/D translocation and 3 instances of an extra, small, metacentric chromosome in addition to a normal karyotype were observed.