[Significance of genetic and environmental factors in the occurrence of chronic bronchitis (a study of twins)].

A study of a sample of 47 pairs of twins with chronic bronchitis made it possible to determine a qualitative and quantitative role of hereditary factors in "exposure" to this disease. A lower inheritability ratio was revealed in chronic obstructive bronchitis as compared to chronic nonobstructive bronchitis indicating leading role of the environmental factors (smoking and industrial hazards) in the development of this type of the disease. The importance of these factors in the etiology of different types of chronic bronchitis is also confirmed.