Relation Between Variation Of Centromeric Alpha Satellite DNA On Human X Chromosome And Aneuploidy

Objective To find an effective method which can be used for studying variation of X chromosome centromeric alpha satellite DNA. We probe into the relation between variation of human X chromsome centromeric alpha satellite DNA and aneuploidy by Klinefelter syndrome patients.Methods The multi-copies of a 2kb tandem repeat unit in alpha satellite DNA were simultaneously amplicated with reasonable primers by (rep)PCR. Mutation frequency and position in the repeat unit were detected by analysis of DNA sequence.Results We observe 1774bp, 1411bp, 570bp, 562bp and 220bp(three short fragments are from deletion of 2kb tandem repeat unit in alpha satellite DNA) in Klinefelter patients and normal karyotype controls. There are fragments of 1774bp and 1411bp in all of experiment samples, but the relative frequency of 570bp, 562bp and 220bp were significantly different between Klinefelter syndrome patients and normal karyotype controls. The former is higher than the latter (P＜0.05).The result of logistic regression analysis indicate that appearance of three or two short fragments together is a risk factor of aneuploidy formation. Recombination locus of deletion within 1411bp and 1774bp fragments were comfirmed by cloning and sequencing.Conclusion Both normal karyotype controls and Klinefelter syndrome patients have fragment deletion in 2kb tandem repeat unit of X chromosome centromeric alpha satellite DNA, but the relative frequency of fragment deletion in Klinefelter syndrome patients is higher than normal karyotype controls. Locus of fragment deletion occur frequently in the three positions, two of them are described for the first time by us. Appearance of three or two short fragments together is a risk factor of aneuploidy formation. We think that more frequency of the fragment deletion in tandem repeat unit perhaps is an important causation of aneuploidy formation.