Quantitative pyrosequencing of heterozygous single nucleotide polymorphisms for rapid diagnosis of Down's syndrome / 中华医学遗传学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To establish a method to detect Down's syndrome through quantitative pyrosequencing of the heterozygous single nucleotide polymorphisms (SNPs) on the chromosome 21.</p><p><b>METHODS</b>An improved allele-specific-amplification was used to screen heterozygous SNPs on the chromosome 21 from 84 normal samples. Pyrosequencing was used to quantitatively determine the ratio between the two alleles of a heterozygote, and the diagnosis of Down's syndrome was thus carried out based on the ratio.</p><p><b>RESULTS</b>By genotyping 84 genomic DNA samples from normal Chinese population, 6 SNPs with a relatively high level of heterozygosity were screened out. Heterozygote coverage of 92.9% was achieved by using a panel of 6 SNPs on the chromosome 21. Ten clinical samples from Down's syndrome patients were quantitatively determined by pyrosequencing, and 9 samples were accurately diagnosed by comparing the ratio of the two alleles. The pyrosequencing results showed that the ratio of the two alleles were 21 or 12 for the Down's syndrome patients.</p><p><b>CONCLUSION</b>The method has the advantage of a low cost, simple process, and time-saving operation and could be potentially applicable to the rapid diagnosis of Down's syndrome.</p>