Mean FMR1 mRNA in blood lymphocytes assessed using PrimeFlowTM showed less variation in relative terms at 1.026 ± 0.08 FMR1 mRNA/dapB MFI and 0.905 ± 0.15 FMR1 mRNA/dapB MFI in FXS participants and 1.197 ± 0.08 FMR1 mRNA/dapB MFI and 1.164 ± 0.06 FMR1 mRNA/dapB MFI in healthy participants at visit 1 and visit 2, respectively, compared to hair follicle FMR1 levels using qRT-PCR. Here, FMR1 is linked to fragile X syndrome.