Very early-onset sporadic Alzheimer's disease with a de novo mutation in the PSEN1 gene.

We report a 22-year onset age man diagnosed with rapidly progressing early-onset Alzheimer's disease with predominant extrapyramidal symptoms as the initial presenting symptoms and V391G mutation in presenilin 1 gene (PSEN1) was founded. The unaffected parents of the proband are not carriers of the mutation but have histories of extrapyramidal diseases, suggesting de novo origin of V391G mutation. The Val391Gly variation widens the number of PSEN1 mutations responsible for early-onset Alzheimer's disease with extrapyramidal phenotype and would help to establish a functional map of presenilin 1 protein architecture.