Amplicons from individuals with different genotypes for the exon 4 splice acceptor site SNP were digested with the restriction enzyme AciI (upper panel) and DNA sequenced (lower panel). Undigested samples, UD and digested samples, D. Arrows indicate the polymorphic nucleotide. In an individual homozygous for the splice acceptor site (AG, middle panel) no AciI digest site is present. In an individual homozygous for loss of the splice acceptor site (GG, right panel) the 158 bp amplicon is cut into fragments of 104 and 54 bp. In an individual heterozygous for the AG splice acceptor site (RG, left panel) both alleles are present and the amplicon is only partially digested.