Simultaneous Detection of Trisomies 13, 18, and 21 with Multiplex Ligation-Dependent Probe Amplification–Based Real-Time PCR

Abstract

BACKGROUND Trisomies 13, 18, and 21 account for the majority of chromosomal aneuploidies detected in prenatal diagnosis. Diagnosis of these trisomies relies mainly on karyotype analysis. Several molecular methods have been developed for trisomy detection, but performance or throughput limitations of these methods currently constrain their use in routine testing. METHODS We developed multiplex ligation-dependent probe amplification–based real-time PCR (MLPA/rtPCR) to simultaneously detect these 3 trisomy conditions with a single reaction. We applied the method to DNA isolated from 144 blinded clinical samples that included 32 cases of trisomy 21, 11 cases of trisomy 18, 1 case of trisomy 13, and 100 unaffected control samples; results were compared with karyotype analysis. RESULTS As judged by the results of the karyotype analysis, MLPA/rtPCR correctly detected all 44 cases of trisomy in the analysis of the blinded clinical samples. The method was able to detect a change in chromosome dosage as low as 1.2-fold. CONCLUSIONS This novel PCR-based technology simultaneously identified 3 types of trisomy in a single reaction and accurately detected trisomy with mosaicism, while reducing assay times and costs compared with conventional methods. The MLPA/rtPCR approach may have applicability in noninvasive prenatal diagnosis with maternal blood samples.