Natera publishes experience study in twin pregnancies in Prenatal Diagnosis

Natera announced the publication in Prenatal Diagnosis of a clinical experience study in twin pregnancies featuring its Panorama single nucleotide polymorphism, or SNP-based noninvasive prenatal test, or NIPT. These real-world results are consistent with previously reported performance of NIPT in twins, and reinforce the importance of Panorama's unique ability to determine zygosity and incorporate this information into risk assessments. In this study, from a pool of 18,984 twin pregnancy results over a 27-month period in Natera's laboratory, investigators sought clinical outcomes from all cases reported as high-risk. Outcomes were obtained for 105 high-risk cases, representing 51.2% of the reported high-risk results. Key findings include: across all twins with cytogenetic confirmation, the positive predictive value, or PPV, of screening for trisomy 21 was 88.7%. When cases with findings suggestive of aneuploidy are included, the PPV for trisomy 21 was 90.4%. Dizygotic twin cases confirmed cytogenetically had an estimated PPV of 88.1% for trisomy 21, and 85% for all aneuploidies, the first time NIPT PPVs have been reported specifically for DZ twins. Monozygotic twin cases, both those confirmed cytogenetically and with findings suggestive of aneuploidy, had a PPV of 100% for trisomy 21 and trisomy 18. This study provides additional evidence to earlier findings that aneuploidy rates are higher in DZ than in MZ twin pregnancies.1 In this study, DZ twins had a positive call rate 8-fold higher than MZ twins.