Bone problems and cystic fibrosis

A recent study by Dr Christina Haston, a researcher of the McGill University Health Centre research Institute, sheds some new light on the bone problems that generally accompany cystic fibrosis.

Dr Haston's study is pointing at genetics as contributing to this bone frailty, a finding which may have some implications in changing therapeutic practices. The article was published on February 1, 2008 in the American Journal of Respiratory and Critical Care Medicine.

The medical community generally considers the bone fragility associated with cystic fibrosis to be multifactorial. It is thought to be a consequence of the mutation of the Cftr gene, the gene responsible for cystic fibrosis, of the pancreatic disease associated with cystic fibrosis and of the treatment with steroids to facilitate breathing.

The study showed that mice with a Cftr gene mutation have a bone mineral density and bone mass that are significantly lower than those of control mice. This difference occurs without the pancreatic insufficiency seen clinically and in the absence of steroid treatment.

This conclusion clearly defines cystic-fibrosis-related bone problems as an additional pathology stemming from the Cftr mutation and not as a side effect of treatment. This may have some therapeutic consequences as it opens an avenue for defining a targeted treatment in mice.

Although the precise mechanism that links this mutation to bone development is unknown, studying these mice at different ages corresponding to childhood, adolescence and adulthood has shown that the bone structures of mice with the Cftr mutation get closer to the norm as the mice age; in other words, the genetic mutation seems to just slow bone growth and not prevent it. However, this partial conclusion requires further study to be confirmed.