Alzheimer disease PS-1 exon 9 deletion defined.

To the editor—The clinical, pathological, and genetic analyses of a Finnish pedigree (Finn2) with early-onset inherited Alzheimer disease (AD) have been reported1. This family demonstrated linkage to the PS1 region of chromosome 14, and analysis for PS1 mutations by RT−PCR and immunoblot demonstrated heterozygous deletion of exon 9, which has been shown to cause early-onset AD2. However, unlike a previously described family2, no splice acceptor site mutation was detected in Finn2, suggesting the presence of either a small genomic deletion that included exon 9 or of mutations elsewhere that could affect splicing.