FMR1 and fragile X syndrome: Molecular testing for Fragile X Syndrome (FXS) was performed using the AmplideX® PCR assay (Asuragen, Austin, TX, USA) for CGG repeat sizing, and the FMR1 promoter methylation status was evaluated with the AmplideX® mPCR FMR1 Kit (Asuragen®, Austin, TX, USA), according to the manufacturer’s protocol (see SI).