Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder with significant cognitive and functional impacts. Genetic factors, particularly the APOE gene and its allelic variants (ε2, ε3, ε4), play a critical role in AD susceptibility. This study analyzed the allelic frequency and distribution of APOE polymorphisms in three provinces of Castilla y León (León, Soria, Salamanca), Spain, to explore their potential relationship with AD risk. Genotypes were determined using polymerase chain reactions, and statistical analyses revealed significant regional variations. The ε3/ε3 genotype was the most prevalent overall, while the ε3/ε4 genotype predominated in specific areas like Ponferrada. The absence of homozygous ε4 individuals in Soria contrasts sharply with higher frequencies in Salamanca. These differences suggest historical and migratory influences on genetic variability. Identifying regional genetic patterns enhances our understanding of AD risk and supports the development of targeted preventive strategies. Early detection of high-risk alleles could improve patient outcomes, reduce healthcare burdens and inform public health policies.