A novel Leu171Pro mutation in presenilin-1 gene in a Mexican family with early onset Alzheimer disease.

A search for mutations in exons 6, 7, 9 and 12 of the PS1 gene in four Mexican families with Early-Onset (36-40 years) Alzheimer Disease yielded the discovery in one family of a T-->C mismatch in exon 7 which correspond to nucleotide 760 of cDNA, leading to a Leu171Pro mutation. The pedigree analysis and the literature data strongly suggest an etiopathogenic relationship of the mutation with the disorder.