WT-GFP mice show minimal overt phenotype. (A) Schematic representation of MeCP2 with an EGFP tag. Missense mutations analysed in this study (T158M, R133C and R306C) are shown in relation to the MBD and NID. (B) Levels (mean ± SD) of Mecp2 transcripts in WT-GFP mouse brain (n = 9) compared with WT littermates (n = 9), expressed relative to Cyclophilin A transcript (CycA). (C) Representative western blot and quantification comparing MeCP2 protein abundance in WT-GFP mouse brain (double arrow-head, n = 6) versus WT littermates (single arrow-head, n = 6). Gamma tubulin (GT) served as an internal control. Mean ± SEM plotted. (D) The Kaplan–Meyer plots showing survival of WT-GFP mice (n = 8) compared with their WT littermates (n = 8) and Mecp2-null mice [Ref. (18)] (n = 24). (E) Growth curve showing average weight of WT-GFP mice (n = 8) compared with their WT littermates (n = 8). Using repeated measures ANOVA, the difference was consistent and significant (P < 0.001) over time, but at any single time point, the difference was not significant. (F) Phenotypic scoring (see the text) of WT-GFP or WT mice. For comparison, Mecp2-null scoring is shown. (G–I) WT-GFP mice (n = 9) and their WT littermates (n = 10) were compared using three behavioural tests: (G) the hanging-wire test, (H) the elevated plus maze, and (I) the accelerating rotarod showing individual mean latencies (dots) and cohort mean latency (line) for each of three days of trials. Statistical analysis took all trials into account. Statistical tests were unpaired two-tailed t-test (B, C and E) and the Kolmogorov–Smirnov test (G–I). All behavioural paradigms were conducted on animals aged 8–10 weeks, and biochemical analyses were conducted using tissues from adults aged 6–12 weeks. Asterisks denote the following P values: *P < 0.05, **P < 0.01 and ***P < 0.001.