Structure and expression of Mecp2 mutant alleles. A. Genomic structure of Mecp2 mutations . a. Wild-type Mecp2 gene. MBD, methyl-CpG binding domain; TRD, transcription repression domain. White or hatched: coding sequence. Grey: non-coding parts of transcript. Exons 1 and 2 that are alternatively spliced, and intron 2, are not drawn to scale. Horizontal bar above exon 4 denotes location of the amplicon analyzed by qRT-PCR (in Figure 1B) b. The Mecp2
tm1.1Jae (J-allele) mutant has a deletion of exon 3 that encodes the N-terminal half of the MBD. c. In the Mecp2
tm1.1Bird (B-allele) mutant, exon 3, the coding portion of exon 4 and part of the 3'UTR are deleted. This larger deletion eliminates ~ 97% of the coding sequence. B. Real-time quantitative RT-PCR analysis of Mecp2 expression in cerebellum . Using primers within the deleted region, Mecp2 transcript was undetectable in mutant mice with the B-allele, when four wild-type and four mutant samples were compared at 8 wk. This proves the specificity of the primers. In mice with the J-allele, mean Mecp2 expression was higher in the mutants, but this difference was not statistically significant (P = 0.11), when six wild-type and seven mutant samples were compared at 8 wk.