Early-onset Alzheimer's disease caused by a novel mutation at codon 219 of the presenilin-1 gene.

Mutations in the presenilin 1 (PS1) gene are responsible for approximately 50% of early onset autosomal-dominant Alzheimer's disease cases. A PCR based mutation detection method, chemical cleavage of mismatch, was used to detect a novel PS1 mutation in the coding sequence of the PS1 gene. Sequencing confirmed a T to C transition altering a leucine to proline at codon 219 of the PS1 gene. This is a novel mutation in exon 7 of the PS1 gene occurring outside the transmembrane regions of IV and V.