Final answer:
Ashkenazi Jews have high levels of the 84GG allele of the GBA gene due to a founder effect. The 84GG allele provides protection against Tay-Sachs disease and may increase the risk of Gaucher disease. The specific formation of the allele and its discovery likely involved genetic studies and analysis of the Ashkenazi Jewish population.
Step-by-step explanation:
Ashkenazi Jews have high levels of the 84GG allele of the GBA gene due to a founder effect. The founder effect occurs when a small group of individuals with a particular trait or allele establishes a population, resulting in a high frequency of that trait or allele in subsequent generations.
In the case of Ashkenazi Jews, it is believed that a small group of individuals carrying the 84GG allele migrated to Eastern Europe and became the founders of the Ashkenazi population.
The 84GG allele provides a selective advantage against a viral infection known as the Tay-Sachs disease. Individuals with one copy of the 84GG allele are protected against Tay-Sachs disease, while those with two copies may have an increased risk of developing Gaucher disease.
The estimated formation of the 84GG allele is not explicitly mentioned in the information provided. However, it can be inferred that the allele formed as a result of a mutation that occurred in the ancestral population of Ashkenazi Jews.
The specific discovery of the allele may have been made through genetic studies and analysis of the Ashkenazi Jewish population's genetic history and inheritance patterns.