How prevalent is this disease in a population?

Tay-Sachs disease is a very rare disease of the nervous system and is very common within the Eastern and Central European populations. It is most common among the Ashenazi Jewish population where one out of every twenty-seven people have or carry this disease. It is also more prevalent in some French-Canadian communities of Quebec, Old Order Amish community in Pennsylvania, and the Cajun populations of Louisiana. Tay-Sachs disease is very rare among the general population.