Objective:To study the variation of X chromosome centromeric Alpha Satellite DNA in Klinefelter’s syndrome patients

their parents and normal individuals and to discuss the mechanism of Klinefelter’s syndrome X chromosome nondisjunction.Methods:The multi-copies of a 2Kb tandem repeat unit on X chromosome of centromeric Alpha Satellite DNA were simultaneously amplified with reasonable primers by (representative sampling of multiple repetitive units

rep)PCR

and the mechanism of X chromosome aneuploidy resulted by abnormal structure of centromere was investigated.Results:1774bp

570bp and 1410bp

583bp

220 bp (three short fragments are resulted by deletion in alpha satellite DNA) were detected in Klinefelter’s syndrome patients

their parents and normal karyotype controls.There were 1774bp and 1410bp DNA fragments in all of samples.The relative frequencies of 570bp and 583 bp were significantly higher in Klinefelter’s syndrome patients than in normal karyotype controls

the 220bp was not found significantly different in the three groups.Conclusion:Deletion in the region of Alpha Satellite DNA is present at centromeres of all human X chromosome

while Klinefelter’s syndrome patients and their parents show higher frequency than normal individuals.These results imply that analysis of deletion on X-specific αsatellite of the parents during the pre-pregnancy and pregnancy plays a important role either in estimating the risk of repruducing Klinefelter’s syndrome or in providing the guideline for prenatal chromosome diagnosis of villus and amniotic fluid.