INTRODUCTION: We have previously demonstrated platelet hyperreactivity in cystic fibrosis (CF) patients. Carriers of one CF mutation (heterozygotes) have been shown to have abnormalities related to the presence of only one-half the normal amount of CF transmembrane conductance regulator protein. Platelet hyperreactivity in CF heterozygotes would be an important cardiovascular risk factor, since approximately 1 in 25 Caucasians is a CF carrier.

MATERIALS AND METHODS: We used highly sensitive assays of platelet activation to assess the difference between 16 CF heterozygotes and 16 age- and sex-matched healthy controls without CF mutations.

RESULTS: We found no difference in platelet activation between CF heterozygotes and controls.

CONCLUSIONS: The 50% reduction in the CF transmembrane conductance regulator protein in heterozygotes is insufficient to cause platelet activation.