19 May Can I Inherit Alzheimer’s Disorder
Inherit Alzheimer’s Disorder
If your parents or grandparents develop Alzheimer’s Disorder it is understandable to worry that you, or your children, may develop the disease. Here we explore whether Alzheimer’s Disorder is genetic.
Which genes are linked to inherit Alzheimer’s Disorder?
There is considerable ongoing investigation into Alzheimer’s Disorder, and the genetic indicators of the illness.
To date there have been two kinds of gene identified in people with Alzheimer’s Disorder. These are known as ‘risk genes’ and ‘deterministic genes’.
The risk genes for Alzheimer’s Disorder have been identified on chromosomes 1, 14, 19 and 21. The apolipoprotein E-e4 – or APOE-e4 – gene has specifically been linked to late-onset Alzheimer’s Disorder, and is found on chromosome 19.
Inheriting this gene increases the risk of developing late-onset Alzheimer’s disease.
Will I definitely develop Alzheimer’s Disorder if I have the APOE-e4 gene?
Most people with Alzheimer’s Disorder have the gene, and inheriting it from one or both parents does increase the risk of developing late-onset AD.
However; it does not mean that you will definitely develop Alzheimer’s. The risk of developing the disease is greater than that of someone without the gene, but it is by no means a certainty.
Many people who have the APOE-e4 gene do not develop Alzheimer’s Disorder and there are many people without the gene who do.
This means that though there are some genetic links found in people with Alzheimer’s Disorder there are no definitive answers as to whether late-onset Alzheimer’s is genetic.
Familial Alzheimer’s Disorder.
As well as the APOE-e4 gene – the ‘risk gene’ – there is more conclusive proof of a ‘deterministic gene’ found in familial Alzheimer’s Disorder.
This gene is found in a very small proportion of people who have the illness. Some studies put the figure as low as 1%, others at closer to 5%.
These cases are usually early-onset Alzheimer’s Disorder, with symptoms beginning in the person’s 30’s and 40’s, rather than their 60’s as in late-onset AD. Many members of the family, across multiple generations, are affected.
Chromosome 21 has been found to contain the familial AD abnormalities, in the proteins amyloid precursor protein (APP) presenilin-1 (PS-1) and presenilin-2 (PS2).
Cases of people with the familial Alzheimer’s Disorder genes are very rare compared to those with the risk gene. However, those with the gene will definitely develop Alzheimer’s Disorder, most probably early-onset AD.