cDNA sequence from the 3 bands amplified in the patient for exons 20 to 28. (A) Sequence from 984-bp band showing homozygosity for the wild-type nucleotide (G) at nucleotide (nt) 3538, codon 1180. (B) Sequence from the 984-bp band shows that exon 25 is spliced to exon 26. (C) The 825-bp band has exon 26 spliced out, therefore exon 25 is spliced to exon 27. The reading frame of the message remains intact. However, an amino acid change results (Pro to Arg) where the last nucleotide of exon 25 pairs with the first 2 nucleotides of exon 27. (D) Sequence from the 984-bp band shows that exon 22 is spliced to exon 23. (E) Sequence from the 684-bp band revealed that exon 23, in addition to exon 26, was skipped. This sequence demonstrates the in-frame splicing of exon 22 to exon 24. No amino acid changes result from the in-frame exon skipping.