[Clinical implementation of non-invasive prenatal study for detecting aneuploidies by fetal DNA based on single nucleotide polymorphisms: two years in Mexico].

Background: Recent data have shown that non invasive prenatal test (NIPT) for the detection of fetal aneuploidies (chromosomes 13, 18, 21, X, Y, and triploidy) by cell free fetal DNA in maternal blood (cfDNA) is a clinical reality, with detection rates > 99% and false positive rates of 0.1%. Results that exceed the first trimester screening.

Objective: To describe our experience of 2 years integrating NIPT by cfADN in its variant of single nucleotide polymorphism (SNPs) as a screening method for the detection of common aneuploidies, since nine weeks of gestation.

Patients And Methods: Observational prospective study from March 2013 to February 2015. Women with a singleton pregnancy were offered conventional prenatal screening fetal aneuploidy and or new alternative NIPT-SNPs.

Results: 270 women were included,the mean maternal age was 35.3 years with a mean gestational age of 11.85 weeks. The result was obtained in 98.5%, with an average report time of 7.5 working days. Blood collection was repeated in fifteen patients, obtaining the result in eleven. The NIPT tested positive for ten cases, 8 for trisomy 21, one for trisomy 18 and one trisomy 13.

Conclusions: We describe our first two years of integrating NIPT-SNPs to obstetric private practice, that is an alternative screening with the potential to be incorporated into theexisting algorithms in prenatal care, from the ninth week of gestation. We expect this information will motivate a debate on the issue of prenatal screening and get to improve obstetric care and genetic counseling in Mexico.