Early detection of chromosomal aneuploidy in miscarriage and aborted embryos referred to forensic genetics’ laboratories by STR sequence analysis

The most common aneuploidies include chromosome 21 trisomy (Down syndrome), chromosome 18 trisomy (Edward syndrome), chromosome 13 trisomy (Down syndrome), chromosome 21 trisomy (Patau syndrome), chromosome X monosomy (Turner syndrome) and Klinefelter syndrome (XXY). On the other hand, spontaneous abortion is common in the first trimester which in the 50% of cases are based on chromosomal abnormalities and may repeated in 2-5% of next pregnancies. Nowadays, screening and diagnostic test for such aneuploidies in fatal period or neonatal phase are based on traditional karyotype which at least 15 days to develop. One of the benefits of applying short tandem repeats (STRs) in molecular studies and screening of chromosomal abnormalities, is the capability of reproducibility of this sequence. Synchronize reproducing capability in multiple loci, high sensitivity and specificity and capability of the analysis of huge data with less burden and time, are some of the impacts of STR application in the screening of chromosomal abnormalities. In this study, the validity of applying STRs for screening of common chromosomal aneuploidy (Down syndrome) have been assessed using data from affected people. After getting the letter of satisfaction from each case next of kin, blood samples from 25 Down syndrome clientele who have been admitted in Isfahan legal medicine department, have been saved on FTA cards. DNA has been extracted from blood samples which then amplified using Amp F STR Identifier kit with PCR. Resultant STR profiles have been visible using ABI capillary electrophoresis and have been analyzed by Gene-Mapper software. Presence of three different alleles in D21S11 locus has been reported in 21 cases out of 25. Application of this technique in rapid screening of chromosomal aneuploidies during pregnancy and also in aborted fetus can be extended.