Fig. 2

A, Schematic diagram of CCM2 exons 1–4 including the alternate exon 1. The boxes represent the exons, the primary transcription start codon in exon 1, secondary transcription start site in alternate exon 1, and the reporter SNP in exon 2 (rs2107732) are indicated, and the arrows below the exons indicate the primers used for RT-PCR. B, The top tracing for each column is the sequence of genomic DNA from an unaffected individual (left) and an affected individual (right) both also heterozygous at SNP rs2107732 in exon 2. The second set of tracings show RT-PCR products from the same unaffected and affected individuals using primers in exons 1 and 4 (black arrows). Transcripts from both alleles are present in the unaffected family member, but only one transcript is seen in the affected individual, with the transcript derived from the mutant allele being absent. The last tracing shows the RT-PCR product from the affected individual using primers in alternate exons 1 and 3 (red arrows). Transcripts from both alleles are present in the affected individual when transcription initiates downstream of the mutation.