Genetic basis of asthma.

Abstract

Asthma is a chronic, inflammatory disease which affects individuals of all age groups. Most commonly, it is seen in children and young adults. The prevalence of asthma in India has been variably reported in the past1. The two recent studies report the prevalence of about two per cent in the general population2,3. The Indian Study on Epidemiology of Asthma, Respiratory symptoms and Chronic bronchitis (INSEARCH) employed a cross-sectional survey design using a standardized, validated questionnaire for interviewing a population sample of 169575 individuals selected in a randomized fashion at 12 different centres across India2. In the second study, the investigators used the data from India's third National Family Health Survey (NFHS-3; 2005-2006) and reported the prevalence of self-reported asthma3. The prevalence in children is generally reported to be higher. Multiple risk factors, both genetic and environmental are important in the aetiology of asthma. Exposure to different allergens (such as the pollens, house-dust mites), micro-organisms, chemicals, vapours, fumes and dusts can precipitate asthma, but cannot alone be blamed to cause asthma. On the other hand, asthma is not a pure genetic disorder. It arises de novo in a large number of patients without the presence of any family history. Presumably, the environmental exposures produce asthma in the genetically susceptible individuals.