Alzheimer'S Disease Genetic Variants represents an important genetic factor in neurodegenerative disease research. This page provides comprehensive information about its role in disease mechanisms, genetic associations, and therapeutic implications.
This index provides a comprehensive guide to genetic variants associated with Alzheimer's disease (AD), the most common neurodegenerative disorder affecting over 6 million Americans. Genetic factors play a critical role in both early-onset familial AD and late-onset sporadic AD, with different variants conferring varying levels of risk from causative mutations to protective alleles.
Alzheimer's disease genetics fall into three main categories:
The amyloid precursor protein gene on chromosome 21q21.3 encodes the protein that is cleaved to produce amyloid-beta peptides. Pathogenic mutations lead to increased amyloid production.
| Mutation | Pathogenic Effect | Age of Onset |
|---|---|---|
| Swedish (K670N/M671L) | Increased Aβ production | ~50-60 years |
| Arctic (E22G) | Aβ protofibril formation | ~50-60 years |
| Flemish (A692G) | Increased Aβ production | ~45-55 years |
| Dutch (E693Q) | Vascular amyloid deposition | ~40-50 years |
| Indiana (V717I) | Altered Aβ ratio | ~50-60 years |
| London (V717I) | Altered Aβ42 ratio | ~50-60 years |
Related Pages:
Presenilin 1 (chromosome 14q24.3) is the catalytic component of the gamma-secretase complex that cleaves APP to generate amyloid-beta peptides. Over 300 pathogenic mutations identified.
| Mutation Class | Effect | Typical Onset |
|---|---|---|
| Missense mutations | Reduced gamma-secretase activity | 30-50 years |
| Large deletions | Complete loss of function | Very early onset |
Related Pages:
Presenilin 2 (chromosome 1q42.13) has similar function to PSEN1 but with less severe phenotypic effects. Fewer than 100 pathogenic mutations known.
| Variant | Effect | Age of Onset |
|---|---|---|
| N141I (Volga German) | Increased Aβ42 | ~50-65 years |
| M239V | Variable penetrance | Variable |
Related Pages:
Apolipoprotein E (chromosome 19q13.32) is the strongest genetic risk factor for late-onset AD. Three common alleles (ε2, ε3, ε4) encode proteins with different amyloid-binding properties.
| Allele | AD Risk | Frequency | Protective |
|---|---|---|---|
| APOE ε4 | Highest risk (3-4x per copy) | ~15% | No |
| APOE ε3 | Neutral risk | ~78% | Reference |
| APOE ε2 | Reduced risk (0.6x) | ~7% | Yes |
Related Pages:
Triggering receptor expressed on myeloid cells 2 (chromosome 6p21.1) encodes a receptor on microglia that mediates phagocytosis of amyloid plaques. Rare variants increase AD risk ~2-4x.
| Variant | Effect | Discovery Year |
|---|---|---|
| R47H | Lost ligand binding | 2013 |
| R62H | Reduced function | 2013 |
| T66M | Complete loss | 2012 |
Related Pages:
| Gene | Chromosome | Odds Ratio | Function |
|---|---|---|---|
| BIN1 | 2q14 | 1.13 | Amphiphysin, synaptic function |
| CLU | 8p21 | 0.86 | Clusterin, complement regulation |
| PICALM | 11q14 | 1.14 | Clathrin-mediated endocytosis |
| CR1 | 1q32 | 1.18 | Complement receptor 1 |
| CD33 | 19q13 | 1.12 | Sialic acid receptor |
| ABCA7 | 19p13 | 1.23 | Lipid transport |
| EPHA1 | 7q34 | 0.90 | Ephrin receptor |
| PLD3 | 19q13 | 1.25 | Phospholipase D3 |
| TYROBP | 19q13 | 1.24 | ITAM adapter |
| UNC5C | 4q33 | 1.23 | Netrin receptor |
Related Pages:
Understanding AD genetics informs therapeutic development:
The study of Alzheimer'S Disease Genetic Variants has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.