6. From the answers below, what is the most likely reason for the large number of tyrosinemia cases in Chicoutimi. Explain the reason for your answer.

(A) A high mutation rate.
(B) A selective advantage for tyrosinemia in this part of Quebec.
(C) Founder effect.
(D) Nutritional patterns in the people; large quantities of tyrosine in the diet.
(E) Pleiotropy where the allele for tyrosinemia has beneficial effects as well as harmful effects.

Reason for your choice:

There is no reason to expect a high mutation rate (answer A) or selective advantage (answer B) for tyrosinemia in Quebec. Since it is a genetic disease, answer D is unlikely. Answer E is conceivable but why should it show up only in Chicoutimi? (C) is the most likely answer since it is reasonable to predict Chicoutimi is a small community. (In fact, the Canadian geneticist Dr. Claude Leberge found the Chicoutimi region was settled by a few dozen families who migrated north from Quebec's Charleuoix County. Most people living there are descendants of the original settlers. The tyrosinemia victims can be traced back to one couple, Louis and Marie Gagne, who emigrated from France. It seems likely that either Louis or Marie had the gene for tyrosinemia and passed it to some of their nine children, and innumerable grandchildren, at least two of whom moved to Charleuoix. Their progeny later moved to Chicoutimi. The significant inbreeding produced a high proportion of people who carried the tyrosinemia gene. This is a classic example of the founder effect.)