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Q&A

Genetics

Poster Session 3

(900) What is the clinical utility and accuracy of single gene NIPT for recessive mendelian disorders?

Wednesday, February 14, 2024
8:30 AM – 10:00 AM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level
Objective: We sought to evaluate the clinical utility and accuracy of commercially available single gene NIPT (sgNIPT) for sickle cell, thalassemia, cystic fibrosis and SMA in at-risk preg pts


Study Design: The MFM dept in our USA regional perinatal ctr performs primary genetic screening/US for nearly 4000 births annually. In 2022, we began offering sgNIPT (Unity) to ethnically diverse patients who were known to be carriers of, or who had family history of SMA, CF, sickle or alpha/beta thal. Fetal/newborn status was assessed via CVS/amnio or newborn screening. The biologic father was routinely offered carrier screening when available. sgNIPT results are designated increased/high risk ( > 1/100; range 1/100 to 9/10) vs decreased/low risk. Small sample size precluded exact estimation of assay accuracy; wide confidence intervals were noted


Results:

During 2022-23, 135 preg pts desired sgNIPT (median gest 18 wks; range 12-36) after the preg pt was found to be a carrier of, affected by, or had family hx of one or more of the above recessive conditions. 80 pts were a carrier of 1 condition, 20 pts were a carrier of 2 dx and 1 pt was a carrier of 3 dx (total 101 carrier pts). 34 pts were not a carrier. 3/143 (2.1%) assays were uninformative. Outcome data was available for all preg. All 5 affected fetuses were classified as high risk while 1 unaffected fetus was labeled high risk (sens 100%, PPV 83%). 129/130 unaffected fetuses were labeled low risk (false pos rate 0.7%) in samples reporting informative results. Two affected preg were terminated while 3 affected preg were continued


Conclusion: sgNIPT for recessive conditions offers refined risk assessment that complements traditional carrier screening and may reliably inform fetal risk status when 1: partner carrier status is unknown/unavailable; 2: paternity is uncertain 3: both partners are carriers. Noninvasive sgNIPT analysis may result in a more precise risk assessment than traditional parental carrier screening alone. Further research with larger populations is needed to rigorously assess the sens/spec and accuracy of sgNIPT for recessive mendelian disorders