تعيين ميزان ژن هاي ناحيه اساسي كروموزوم 21 در نمونه هاي جنيني CVS با استفاده از روش Quantitative Real- Time PCR

Gene dosage analysis of chromosome 21 critical region on chorionic villus samples (CVS) using Quantitative Real-Time PCR

A novel quantitative Real-Time PCR assay on CVS samples was evaluated for rapid prenatal diagnosis of Down syndrome in high risk pregnant women. Chorionic Villus Samples (CVS) was obtained from pregnant women who had the high risk of having fetus with Down syndrome in preliminary screening. Blood samples from Down syndrome patients were used as positive controls. Genomic DNA was extracted using a commercial kit. Gene dosage of DSCAM and DYRK1A2 genes relative to PMP22 gene were determined in Down syndrome and normal samples using quantitative Real-Time PCR. The target/reference genes ratio was calculated using comparative cycle threshold method CAA (t).The results of gene dosage analysis showed the target/reference genes ratio of 1.56±0.09 and 1.02±0.11 in trisomy 21 and normal samples, respectively. The assay was able to demonstrate the presence of three copies of target genes in affected samples. prenatal diagnosis of Down syndrome is feasible by the quantitative Real-Time PCR technique using Chorionic Villus Samples. Currently, cytogenetic analysis is used for detection of trisomy 21 syndrome. These methods are generally time-consuming and also need cultured live cells. In contrast, Real-Time PCR is a high throughput molecular technique with none of the above mentioned limitations. Therefore, Real-Time PCR technique can be suggested as an accurate and sensitive method for rapid prenatal diagnosis of trisomy 21 syndrome.