Establishment of a simple and rapid method to detect MECP2 duplications using digital polymerase chain reaction

Genomic copy number variations (CNVs) can be detected by chromosomal microarray testing. However, upon final diagnosis, other methods may be recommended for a validation method to confirm CNVs. Trio analyses or carrier detection in family members are also frequently required. Previously, fluorescence in situ hybridization and/or quantitative PCR have been used; however, these methods present limitations. The purpose of this study was to establish a simple and rapid method to detect genomic copy numbers. We utilized droplet digital PCR (dPCR) with an intercalation method. Thirteen patients, who were diagnosed with MECP2 duplications via chromosomal microarray testing, were enrolled in this study. Four of their female relatives, who were verified as carriers of MECP2 duplications, were also included. Genomic copy numbers of MECP2 and IRAK1 were analyzed in comparison with reference genes: XIST and AR on the X-chromosome, and RPP30 and RPPH1 on the autosomal chromosomes. As a result, genomic copy numbers of MECP2 were rapidly and precisely detected by the dPCR system established in this study. This method can be widely applied as a diagnostic method to confirm CNVs on other chromosomal regions.