Clinical presentation of early-onset Alzheimer's disease as a result of mutation in exon 12 of the PSEN-1 gene.

Introduction: Mutations in the gene for presenilin 1 (PSEN-1) cause familial, early-onset Alzheimer's disease (EOAD). Diagnosis of EOAD is often a challenge because of the high frequency of atypical presentations. Clinical manifestation of EOAD may vary depending on underlying mutation; specific genetic mutations influence development of specific clinical phenotypes; however, intrafamilial phenotypic heterogeneity has also been noted in some pedigrees.

Case Presentation: We report a case of a 36-year-old woman presenting with progressive behavioral disturbances, dementia, involuntary movements, pyramidal signs, epilepsy, and a family history of early-onset dementia accompanied by involuntary movements. On genetic testing, the mutation at codon 424 (Leu→Arg) in PSEN-1 gene was identified.

Conclusion: Our case describes a new phenotype of a known mutation of PSEN-1 at codon 424.