First results of non-invasive prenatal testing adoption in Moscow

Objective. To analyze the results of prenatal screening using non-invasive prenatal testing (NIPT). To evaluate the advantage of NIPT over a combined prenatal screening in the first trimester of a pregnancy.

Results. High risk of fetal chromosomal abnormalities in relation to frequent aneuploidies according to the results of NIPT was determined in 72 cases out of 5181:50 cases of trisomy 21, 17 cases of trisomy 18 and 5 cases of trisomy 13. It was noted that the level of fetal fraction is affected by body weight and body mass index of patients, the presence of trisomies, and the sex of the fetus.

Conclusion. Preliminary, the introduction of non-invasive prenatal testing in practical health care in Moscow can reduce the number of false-negative cases of fetal chromosomal pathology in the risk group 1:101–1:2500, as well as potentially reduce the number of invasive interventions in the high-risk group. However, due to the small sample size, further research is required.

Random findings in the use of a whole genome noninvasive prenatal test: clinical and ethical aspects

Objective. To analyze the ethical and clinical aspects of accidental findings identification using a whole genome non-invasive prenatal test (NIPT).

Results. In 21 cases, a high risk of rare autosomal trisomies and clinically significant microchromosomal fetus abnormalities or copy number variation (CNV) were revealed.

Conclusion. Accidental findings by whole genome NIPT could increase the efficiency of prenatal diag-nosis, allowing to detect rare trisomies and microchromosomal abnormalities. However, additional re-search is required to formulate clinical guidelines on accidental NIPT detected findings interpretation, on its clinical and ethical aspects.

International experience in organizing non-invasive prenatal testing

Non-invasive prenatal testinging (NIPT) is a relatively new method aimed at detecting fetal chromo-somal aneuploidies by analyzing extracellular fetoplacental DNA in the blood of a pregnant woman. NIPT has high sensitivity and specificity, and many professional communities now recommend its use as a screening method. Since its introduction into clinical practice in Hong Kong in 2011, NIPT has ex-panded rapidly around the world. The experience of various countries in organizing non-invasive pre-natal testing is described in this article.

Prenatal screening and non-invasive prenatal testing regulation in the Russian Federation

Congenital malformations, chromosomal and monogenic disease play a significant role in perinatal mortality and child disability. According to the early prenatal screening results in the Russian Federa-tion in 2018, the overall ratio of chromosomal anomaly prevalence is 1:250–1:300. Currently aneuploidy risk is calculated by using indirect biochemical and ultrasound markers, that have low sensitivity and specificity which can cause false positives and false negative results leading to unreasonable invasive procedures or missing chromosomal anomalies. It is well known that cell-free fetal DNA is detected in maternal blood. Whole‐genome sequencing based non-invasive prenatal testing (NIPT) can detect fetal chromosomal aneuploidy with high sensitivity as early as 10 weeks into pregnancy. The accuracy of determining fetal sex is also high: sensitivity and specificity are 98,9% and 99,9% respectively. Im-plementing molecular technology into clinical practice is required to improve prenatal diagnosis in the Russian Federation, including Moscow. Integration of NIPT to analyze cell-free fetal DNA will increase the efficiency of fetal chromosomal anomalies’ detection. However, there are some legal and ethical aspects to consider when integrating a new technology for wide-spread use. This review reveals argu-able issues of NIPT integration into widespread clinical practice and possible ways of solving those is-sues.

Adoption of a non-invasive prenatal test (NIPT) in prenatal screening in Moscow: first results

The objective. To assess the effectiveness of including NIPT in the structure of prenatal diagnostics in Moscow.

Results. Among the analysed samples, 117 (2.3%) had a high risk of the following common fetal chro-mosome abnormalities by NIPT: trisomy 21 in 50 cases, trisomy 18 in 17 cases, trisomy 13 in 5 cases, and sex chromosome aneuploidy (SCA) in 22 cases. Additionally, rare autosomal trisomies and/or sub-chromosomal arrangements were revealed in 23 cases. We found associations between cfDNA con-centration and high risk of aneuploidies (particularly trisomy 21) and fetal sex and between low fetal fraction (FF) and body mass index (BMI) as well as maternal weight. Additionally, a high risk of trisomy 21 was associated with the term gestation.

Conclusion. The effectiveness of technological resources that are based on cfDNA testing for detect-ing abnormal fetal chromosome numbers and other chromosomal anomalies is high and reduce rates of false positive results. Therefore, NIPT should be more widely used as a first-line screening method.