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Pulmonary abnormalities in obligate heterozygotes for cystic fibrosis
1Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio.
Insights
Parents carrying the cystic fibrosis gene may experience increased airway reactivity and wheezing, particularly if they have never smoked. This heightened reactivity is linked to poorer lung function, suggesting a potential risk for respiratory issues in cystic fibrosis heterozygotes.
Area of Science:
- Pulmonary Medicine
- Genetics
- Respiratory Health
Background:
- Previous studies suggested increased airway reactivity in parents of children with cystic fibrosis, but focused on a limited, asymptomatic population.
- This study investigates respiratory symptoms in a broader, unselected group of parents.
Purpose of the Study:
- To examine the prevalence of respiratory symptoms, particularly wheezing, in parents of children with cystic fibrosis compared to controls.
- To assess the association between cystic fibrosis heterozygosity, wheezing, and pulmonary function.
Main Methods:
- Cross-sectional study comparing 315 parents of children with cystic fibrosis to 162 control parents (children with congenital heart disease).
- Data collected on respiratory symptoms (wheezing, dyspnoea, cough, etc.), history of lung disease, and smoking status.
- Pulmonary function tests (FEV1, FEF25-75) were analyzed in relation to symptoms and cystic fibrosis carrier status.
Main Results:
- Wheezing was more prevalent in cystic fibrosis parents than controls, significantly so in never-smokers (38% vs. 25%).
- Never-smokers with cystic fibrosis heterozygosity who wheezed had lower FEV1 and FEF25-75.
- Wheezing significantly predicted pulmonary function in cystic fibrosis parents, but not controls.
- Parents of children with cystic fibrosis reported a history of lung disease before age 16 more than twice as often as controls.
Conclusions:
- Cystic fibrosis heterozygosity is associated with increased airway reactivity and symptoms like wheezing.
- Cystic fibrosis heterozygotes experiencing airway reactivity may be at risk for diminished pulmonary function.
- These findings support the hypothesis of a link between cystic fibrosis gene carriage and respiratory health issues.
Abstract:
Parents of children with cystic fibrosis have been reported to have a high prevalence of increased airway reactivity, but these studies were done in a select young, healthy, symptomless population. In the present study respiratory symptoms were examined in 315 unselected parents of children with cystic fibrosis and 162 parents of children with congenital heart disease (controls). The cardinal symptom of airway reactivity, wheezing, was somewhat more prevalent in cystic fibrosis parents than in controls, but for most subgroups this increased prevalence did not reach statistical significance. Among those who had never smoked, 38% of obligate heterozygotes for cystic fibrosis but only 25% of the controls reported wheezing (p less than 0.05). The cystic fibrosis parents who had never smoked but reported wheezing had lower FEV1 and FEF25-75, expressed as a percentage of the predicted value, than control parents; and an appreciable portion of the variance in pulmonary function was contributed by the interaction of heterozygosity for cystic fibrosis with wheezing. For cystic fibrosis parents, but not controls, the complaint of wheezing significantly contributed to the prediction of pulmonary function (FEV1 and FEF25-75). In addition, parents of children with cystic fibrosis reported having lung disease before the age of 16 more than twice as frequently as control parents. Other respiratory complaints, including dyspnoea, cough, bronchitis, and hay fever, were as common in controls as in cystic fibrosis heterozygotes. These data are consistent with the hypothesis that heterozygosity for cystic fibrosis is associated with increased airway reactivity and its symptoms, and that the cystic fibrosis heterozygotes who manifest airway reactivity and its symptoms may be at risk for poor pulmonary function.