Autosomal dominant early onset Alzheimer's disease in the Mexican state of Jalisco: High frequency of the mutation PSEN1 c.1292C>A and phenotypic profile of patients.

Abstract

Mutations in three genes (APP, PSEN1, and PSEN2) are the main cause of the autosomal dominant early-onset Alzheimer's disease (AD-EOAD). In PSEN1, the A431E (c.1292C>A, rs63750083) mutation is suspected to have exerted a founder effect in the State of Jalisco, Mexico. In Guadalajara, Jalisco, Mexico, this mutation was found in 46 index cases evaluated for AD-EOAD. In our genealogical analysis, 301 affected relatives of the mutation carriers were identified, 195 of whom were already deceased at the time of interview. Moreover, 560 descendants had a 50% risk of carrying the mutation, and 348 were potentially at risk. A systematic phenotyping was performed in 39 patients. The mean onset age was 42.5 ± 3.9 years, and no significant difference in onset age was observed between the male and female patients. Furthermore, a substantial clinical heterogeneity and high frequencies of spastic paraparesis, language disorders, and neuropsychiatric symptoms were observed. To our knowledge, the investigated families represent the second biggest population carrying a PSEN1 mutation in Latin America, offering a unique opportunity to study the genetic basis of Alzheimer's disease. Addressing AD-EOAD warrants an integral approach involving a deep understanding of its clinical behavior, as well as counseling protocols and prevention studies.