Familial occurrence of chronic respiratory disease and familial resemblance in ventilatory capacity

Abstract

One of the main hypotheses of the Tecumseh Study is that no matter whether genetic, constitutional or environmental factors are involved, new cases of disease will occur among family members of affected persons. During the second cycle of examinations, 82 per cent of the population were examined. Eighty-nine per cent of these 9226 persons had one or most first-degree relatives who was also a member of the study population. We have found that the prevalences of chronic bronchitis, asthma and allergic rhinitis were higher in the offspring when one or both parents were affected than when neither was. Clustering of these conditions also occurred in affected sibships but there was evidence of disease aggregation among spouses only for chronic bronchitis. There were statistically significant correlations of parents' lung function variables with those of their children and these were greater at younger than older ages and when parent and child were of the same sex. Intraclass correlation coefficients of F.E.V.1.0 scores for two-person sibships were statistically significant and varied with sex and age of the sibs. Statistically significant correlations were also found between F.E.V.1.0 scores of spouses but these were appreciably smaller than those between first-degree relatives. The scores of the variables are age- and height-adjusted and therefore, the resemblances in lung function are not merely a reflection of resemblances in height.The patterns of clustering and resemblance vary with disease as well as with age and sex. They implicate both environmental and genetic factors as determinants of chronic bronchitis, asthma, allergic rhinitis and level of ventilatory capacity.