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389: The yield of Chromosomal microarray analysis in cases of pregnancy termination due to fetal malformations

      Objective

      Chromosomal Microarray (CMA) is the method of choice for genetic work-up in cases of fetal malformations detected prenatally. We assessed the detection rate of CMA in cases of pregnancy termination due to abnormal ultrasound findings.

      Study Design

      71 pregnancies terminated due to abnormal ultrasound findings were included. CMA testing was performed using DNA extracted from fetal tissue (mainly skin) or from the placenta. Data regarding the clinical and family background, outcome of the workup performed during pregnancy and the findings detected by CMA were analyzed.

      Results

      CMA analysis was successful in all cases, with no technical failures.
      CMA was abnormal in 17 cases (23.9%): 5 trisomy 21, 4 trisomy 18, 3 trisomy 13, 1 unbalanced translocation of maternal inheritance, 1 mosaic triploidy and 3 cases of microdeletions/microduplications. Variants of Uncertain Significance (VUS) were detected in 6 cases.
      Pathological CMA results were more likely in cases with maternal age >40 or Elevated risk for Down syndrome according to biochemical aneuploidy screening tests (P= 0.03 and 0.02, respectively). There was no correlation between abnormal CMA results and elevated NT, multiple anomalies, or gestational age at diagnosis.

      Conclusion

      The yield of CMA in cases of pregnancy termination was 23.9%. Analysis can be performed with fetal tissue or placental samples. Although most chromosomal abnormalities are detectable by karyotype, CMA does not require viable dividing cells; hence, it is more practical for TOP work-up. In most cases, diagnosis was followed by practical recommendations for testing in the subsequent pregnancy.
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