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Master Thesis

Performances du test par ADN libre circulant (ADNIcT21) pour le dépistage de la trisomie 21 en cas d'obésité maternelle

Abstract : Introduction. A low fetal fraction (FF) can impair the cell-free fetal DNA (cfDNA) screening test performance for trisomy 21. The probability of having less than 4% FF increases with maternal weight.  Objective. To evaluate the performance of cfDNA test and to study the variations in the FF according to the BMI in a population with a high prevalence of obesity in French Polynesia. Methods. In two years, all patients with singleton pregnancy and an indication of cfDNA test were included, excluding fetuses with a morphological abnormality. We determinate the overall cfDNA test performance (sensitivity, specificity, positive and negative predictive values, non-response rate). The patients were classified according to their BMI for a subgroup analysis of the measurement of the FF. Results. Two hundred and seventy patients were included and 42.6 % of the patients had a BMI > 30kg/m². The sensitivity and specificity for trisomy 21 test were respectively 100% and 99.6 %. The positive and negative predictive values were respectively 75% and 100%.  The non-response rate was 0.74 % at the first sample and null after a second sample. The analysis of the FF medians according to BMI showed a significant decrease in obese compared to non-obese patients (p <0.001).  Conclusion. CfDNA test can be performed in a population with both high risk of aneuploidy and high prevalence of maternal obesity. Repetition of the sampling in second trimester allows to get a result if the FF was low.
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Loriane Franchinard. Performances du test par ADN libre circulant (ADNIcT21) pour le dépistage de la trisomie 21 en cas d'obésité maternelle. Gynécologie et obstétrique. 2018. ⟨dumas-02481842⟩



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