Deficit of osteoprotegerin release by osteoblasts from a patient with cystic fibrosis

To the Editors: Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations of the CF transmembrane conductance regulator (CFTR), a cyclic adenosine monophosphate (cAMP)-dependent anion channel expressed mostly in epithelia. Bone deficiency is commonly seen in patients with CF and begins at a young age. Low bone mass affects children and young adults with CF and is associated with significant morbidity due to fractures and decreased lung function. Brittle bones in CF disease have been confirmed by densitometric data, the presence of fractures, and impaired quality of life of young and adult patients [1]. Whether or not this is caused by bone disease around puberty due to a poor acquisition of peak bone mass and worsens with age, lower bone mineral density (BMD) gains are already being observed in CF children with mild disease and normal nutritional status, suggesting that CF-related low BMD may, in part, be due to a primary defect in bone metabolism [2]. In human bone cells, the expression of CFTR protein has been identified by immunohistological observations [3]; we further reported the expression of CFTR mRNA and protein in primary …