FMR1 c.*746 site modulates steady-state and activity-dependent reporter activity. (A) Results of three independent luciferase assays using mutagenized vectors in HEK293 cells. Reference allele at c.*746, T; patient allele, C. Data shown are the mean ± SD. (B) A 17-bp deletion in the vectors that deletes the U-rich locus including the 746 site (indicated by a horizontal bracket and red lettering, respectively) was used in luciferase assays. Results are the mean of three independent experiments ± SD. (C) Luciferase assay in WT mouse primary cortical neurons (E17.5) using various vectors with and without DHPG treatment (100 μM, 5 min) ∼24 h posttransfection. Data shown are the mean of four or five independent experiments ± SD. (D) Luciferase assay in Fmr1 KO mouse primary cortical neurons (E17.5) using various vectors with and without DHPG treatment (100 μM, 5 min) ∼24 h posttransfection. Data shown are the mean of four or five independent experiments ± SD. Unpaired two-tailed t test, *P < 0.05. C, control; Del, deletion; P, patient.