Cystic fibrosis mutations in French Canadians: Three CFTR mutations are relatively frequent in a Quebec population with an elevated incidence of cystic fibrosis

Abstract

The French‐Canadian population in the Saguenay‐Lac St. Jean region of northeastern Quebec has an elevated frequency of cystic fibrosis (CF). The average incidence of cystic fibrosis was 1 in 891 births and the prevalence of CF carriers was estimated to be 1 in 15. We tested for 10 mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene in 133 French‐Canadian CF families from Quebec. Ninety‐one families were from the Saguenay‐Lac St. Jean region and 42 families were referred from other regions of Quebec. We detected the CFTR mutation in 93 and 92% of the CF chromosomes in the Saguenay‐Lac St. Jean and the major‐urban Quebec families, respectively. The two groups of French‐Canadian families were significantly different for the proportions of CFTR mutations. The three most common mutations in the Saguenay‐Lac St. Jean families were ΔF508 (58%), 621 + 1G → T (23%), and A455E (8%); and in the major‐urban Quebec families were ΔF508 (71%), 711 + 1G → T (9%), and 621 + 1G → T (5%). These results provide evidence for the role of founder effect in the elevated incidence of cystic fibrosis in the Saguenay‐Lac St. Jean population.