Abstract: Objective：To evaluate the clinical application of the chromosome karyotype of umbilical blood samples in genetic diagnosis. Methods：To analyze retrospectively the data of chromosome karyotype of umbilical blood samples in 2 036 newborns in our hospital from June to December 2013. The chromosome specimen was prepared by the method of conventional peripheral blood lymphocytes culture. Karyotype was analyzed by the G-banding technique. Results：Totally，there were 16 cases（0.79%） of chromosome abnormalities in 2 036 cases，including 13 cases（0.64%） with autosomal abnormalities and 3 cases（0.15%） with sex chromosome abnormalities. There were 3 cases of 21-trisomy（0.15%），a terminal deletion（0.05%），3 cases of inversion（0.15%），a balanced translocation（0.05%），3 cases of Robertsonian translocation（0.15%） and two cases of marker chromosome（0.10%） in those autosomal abnormalities. There were 2 cases of 47，XYY（0.10%） and a 46，XX，del（X）（0.05%） in those sex chromosome abnormalities. There were also 181 cases（8.89%） of polymorphic variation karyotypes. Conclusions：We can increase the rate of prenatal diagnosis by improving the prenatal education. Those newborns should be diagnosed early in neonatal phase if pregnant women with high risks did not get prenatal diagnosis.

Key words: Chromosomes, Karyotyping, Chromosome aberrations, Infant, newborn, Fetal blood