AN ABNORMAL DISTRIBUTION OF DELTA-F508 GENOTYPES IN CYSTIC-FIBROSIS PATIENT REGISTRIES

Delta F508 mutation of the CFTR gene is the most frequent deleterious allele involved in cystic fibrosis (CF). We have studied the distribut ion of the three genotypes, Delta F508/Delta F508, Delta F508/x, x/x, in the American, Canadian and French data registries concerning CF; '' x'' represents the non-Delta F508 mutations. In the three registries t he observed distribution of the three genotypes differs from the expec ted one, calculated according to the Hardy and Weinberg equilibrium. T hree factors could explain this discrepancy : Wahlund's effect, misint erpretation of the molecular diagnosis, or an ascertainment bias in re lation with the severity of the disease. This last factor is the most likely.