Cystic fibrosis is the most common hereditary disease in populations of European 
descent, with its prevalence depending on the populations and ethnic groups 
studied. In contrast to Europe and North America, there is little information 
about this disease in Latin America. Uruguay currently has a human population of 
3,000,000, with a low rate of miscegenation and no remaining isolated Amerindian 
groups. In the present study, we estimated the prevalence of cystic fibrosis in 
this country based on the detection of DeltaF508 mutation carriers in 500 
unrelated individuals and on the frequency of individuals homozygous for this 
mutation within the affected population. The latter was calculated from the 
frequency of the different mutations and genotypes observed in a sample of 52 
previously described patients with confirmed cystic fibrosis. A theoretical 
estimate of the prevalence of cystic fibrosis based on anthropological data 
suggested a frequency of 25 affected individuals/100,000 inhabitants. However, 
our data indicated that the true prevalence in the population was considerably 
lower (6.9 cases/100,000 inhabitants).