HIGHLY ACCURATE ANALYSIS OF HETEROZYGOUS LOCI BY SINGLE-CELL PCR

Single cell PCR is a powerful method for determining the genetic prope rties of individual cells. In the instance of heterozygous loci, howev er, preferential amplification of one allele can lead to allele drop o ut (ADO) of the other allele, Fortunately ADO does not occur in all am plifications, and is usually random when it does occur, with both alle les being equally susceptible to drop out, Therefore pooling of result s from multiple independently amplified cells should greatly improve t he analysis of diallelic loci, and the misdiagnosis rate of diallelic loci should decrease exponentially with the number of cells analysed. We have shown that this is true and that multiplex PCR allows for the simultaneous identification of a cell in a mixture of cells using micr osatellite loci known to be informative, and accurate genotyping at ot her loci, This approach has practical applications to non-invasive pre natal diagnosis where small numbers of fetal cells in the presence of maternal cells must be both identified and genotyped at loci involved in genetic disease.