20-year experience on prenatal diagnosis in a reference university medical genetics center in Turkey

Although cutting edge procedures such as cell-free fetal DNA isolation from maternal blood are now available, invasive prenatal tests are still being used extensively for prenatal diagnosis. The study aims to evaluate the demographic data, indications, and cytogenetic results of 9297 results of patients who underwent prenatal invasive testing for genetic analysis that were referred for the last 20 years in a University Medical Genetics Center.

The records of 8363 amniocenteses, 626 chorionic villus, and 308 cordocenteses samples were retrospectively evaluated and analyzed regarding referral reasons, indications and their cytogenetic results. The total numbers and the percentages of each group were recorded; Chi-square and logistic regression analyses were performed to give the statistical likelihood of different events.

The number of referrals decreased significantly after 2009. Risk of having trisomy 21 as well as trisomy 13 and 18 significantly increased in parallel with advanced maternal age. When the 21–25 age group was compared to the older age groups in terms of having a trisomy 21 pregnancy, the risk doubled in the 36–40, 5 times higher in 41–45 and 10-fold in 46–50 age groups. No significant linear correlation between maternal serum screening test results and trisomy 21 was found, however the difference between the pregnancies whom cut-off value above and below 1/250 in maternal serum screening test were significant.

These data have provided useful information on the frequency of referrals to the reference genetics department, and the feasibility of genetic services. By reviewing the indications and their corresponding results, we can offer invaluable insights that will be useful in genetic counseling and also in the development of more effective genetic strategies.