(A) RT-PCR of CADPS2 mRNA in blood from subsets of patients with ASD (A1–A14) and control patients (C1–C10) following the Sadakata et al. protocols (1). The 661-bp band represents the full-length exon 1–5 fragment of CADPS2 mRNA, while the 328-bp band is a result of exon 3 skipping. Four control samples (C1, C2, C6, and C8) and 4 ASD samples (A3, A7, A8, and A9) were heterozygous for the exon 3–skipped isoform. The flanking marker is a 50-bp ladder. The remaining samples showed only the 661-bp band (data not shown). (B) Alignment of sequences obtained from the 328-bp bands of samples C1, C2, C6, and A9 to human chromosome 7 showed that all sequences lacked exon 3. Sequencing the 661-bp band of A10 (which was representative of other samples not showing the 328-bp band) demonstrated that this fragment does include exon 3, as expected. (C) RT-PCR of blood CADPS2 mRNA using a nested amplification. A single major band (563 bp), indicating the presence of exons 2–5, is shown in all autistic samples. Control sample C14 was apparently homozygous for a 230-bp band that resulted from skipping of exon 3. (D) RT-PCR of cerebellar CADPS2 mRNA from individuals with ASD and control individuals showed that all cerebella contained the exon 3–skipped splice variant as a minor isoform (230-bp fragment). M, low-DNA-mass ladder (Invitrogen).