Genetic diseases established genes

In the rest of this chapter we will look at how this works out in practice, using the example of Alzheimer s disease. Dementia illustrates many of the points we have discussed, such as misleadingly complex genetics. There are several well-established genes that increase the risk of Alzheimer s disease, which seem to have no association with oxidative stress. This disease is therefore a good example of how susceptibility genes that seem unrelated to oxygen are in fact influenced by mitochondria, oxidative stress, and inflammation. 

Examples of a polymorphism include single nucleotide substitutions, insertions and deletions of nucleotides, and repetitive sequences. While most polymorphisms are harmless and part of normal human genetic variations, studies have established links between certain gene polymorphisms and metabolic alterations or human diseases. 

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