The genetics of Alzheimer's disease (AD) has been a focus of extensive research, with significant advancements in understanding the genetic underpinnings of the disease. Family history is the second strongest risk factor for AD, following advanced age, and genetic factors are estimated to play a role in at least 80% of AD cases. The inheritance of AD exhibits a dichotomous pattern: rare mutations in *APP*, *PSEN1*, and *PSEN2* virtually guarantee early-onset (<60 years) familial AD, while common gene polymorphisms, such as the ε4 and ε2 variants of the *APOE* gene, influence susceptibility for ~50% of late-onset AD (LOAD). These four genes account for 30%–50% of the inheritability of AD. Genome-wide association studies (GWAS) have identified 11 additional AD candidate genes, and the identification of rare variants causing LOAD remains an area of active research. The understanding of AD etiology and pathogenesis has been revolutionized by genetic research, leading to the discovery of novel therapeutic strategies aimed at preventing and treating AD. However, up to 50% of the heritability of AD remains unexplained by currently known genes, highlighting the need for further genetic studies to uncover the missing heritability.The genetics of Alzheimer's disease (AD) has been a focus of extensive research, with significant advancements in understanding the genetic underpinnings of the disease. Family history is the second strongest risk factor for AD, following advanced age, and genetic factors are estimated to play a role in at least 80% of AD cases. The inheritance of AD exhibits a dichotomous pattern: rare mutations in *APP*, *PSEN1*, and *PSEN2* virtually guarantee early-onset (<60 years) familial AD, while common gene polymorphisms, such as the ε4 and ε2 variants of the *APOE* gene, influence susceptibility for ~50% of late-onset AD (LOAD). These four genes account for 30%–50% of the inheritability of AD. Genome-wide association studies (GWAS) have identified 11 additional AD candidate genes, and the identification of rare variants causing LOAD remains an area of active research. The understanding of AD etiology and pathogenesis has been revolutionized by genetic research, leading to the discovery of novel therapeutic strategies aimed at preventing and treating AD. However, up to 50% of the heritability of AD remains unexplained by currently known genes, highlighting the need for further genetic studies to uncover the missing heritability.