Objectives: Evaluation of the phenotype-genotype correlation of a specific mucoviscidosis mutation, "Y122X", in Reunion Island. This mutation represents 25% of our cases.
Patients and methods: Retrospective study of a cohort of 84 children presenting cystic fibrosis (CF) during a 5-year period (1994-1998). Diagnosis was based on one or two identified genetic mutations and/or minimum two abnormal chloride sweat tests (Cl > 70 mmol/l). Follow-up of this cohort was performed in the two referral centers of the Island following the French national guidelines (INSERM U 155).
Results: In our population, we identified 10 mutations, of which three of them represented more than 80% of the cases: Delta F508 (51.8%), Y122X (24.4%) and 3120 + 1G --> A (4.8%). The authors report clinical significant differences in children with the homozygote mutation Y122X as compared with children presenting the Delta F508 CF-mutation: failure to thrive affecting mainly the height with, paradoxically, a relatively normal weight development, and a better pulmonary function.
Conclusion: The frequent Y122X CF-mutation reported in "la Reunion" seems to affect mainly height in children with a relatively good nutritional outcome. This failure to thrive does not seem to be of digestive origin. These results suggest that growth gene(s) located nearby the cystic fibrosis transmembrane conductance regulator (CFTR) may have suffered the same segregation than the Y122X mutation or that clusters of this specific Caucasian population known as "petits blancs" in la Reunion are smallest for ethnic reasons.