The genetics of Alzheimer disease

Area of Science:

• Neuroscience
• Genetics
• Gerontology

Background:

• Family history is a major risk factor for Alzheimer disease (AD), second only to advanced age.
• Genetic factors are implicated in at least 80% of AD cases, highlighting the importance of genetic research.
• AD inheritance shows a dual pattern: rare mutations for early-onset familial AD and common polymorphisms for late-onset AD.

Purpose of the Study:

• To review the current understanding of the genetic underpinnings of Alzheimer disease.
• To explore the historical progression and future directions in AD genetic research.
• To elucidate the complex and heterogeneous genetic factors contributing to AD.

Main Methods:

• Review of existing literature on Alzheimer disease genetics.
• Analysis of findings from twin and family studies.
• Inclusion of data from genome-wide association studies (GWAS).

Main Results:

• Rare mutations in APP, PSEN1, and PSEN2 are linked to early-onset familial AD (∼5% of cases).
• Common gene polymorphisms, notably APOE variants (ε4, ε2), affect susceptibility in late-onset AD (∼50% of cases).
• APP, PSEN1, PSEN2, and APOE genes explain 30%-50% of AD heritability; 11 additional AD candidate genes have been identified via GWAS.

Conclusions:

• Alzheimer disease has complex and heterogeneous genetic factors.
• Understanding these genetic influences is crucial for developing targeted AD therapies.
• Continued genetic research, including GWAS, is essential for further unraveling AD's etiology.