BackgroundABO blood group types are hereditary factors that have been shown to affect the blood levels of many antigens and proteins. Some blood groups have surprisingly been shown to be associated with some specific diseases, probably due to yet unexplained altering effects on the immune system or on the levels of other system-specific proteins. Studies conducted previously attempting to relate bronchial asthma and blood groups have had variable results and such studies on a large scale have not been ventured in India. Hence, the significance of the current study, which aims to search for an increased occurrence of bronchial asthma in any one of the ABO blood group phenotypes and additionally in Rh blood groups.ObjectiveThe objective of this study was to analyze the possible association of the ABO and Rh blood group types with bronchial asthma.MethodsThis is an observational study with 475 bronchial asthma patients, and 2052 non-asthmatic individuals belonging to the same geographical zone. After obtaining informed consent, ABO and Rh Blood group testing was done on the study subjects using the hemagglutination method. Chi-squared tests were employed for the comparison of proportions. Statistical significance was agreed upon for an error of 5%.ResultsThe O blood group was predominant in both cases (46.9 %) and controls (36.1%). A chi-square analysis revealed a statistically significant higher percentage of O blood group in patients (χ2: 24.537; degrees of freedom (DF): 3; p-value = <0.01). The cases had more Rh -ve individuals (12%) than controls (8%), which too was statistically significant (χ2: 6.711; degrees of freedom (DF): 1; p-value = 0.01).ConclusionThe present study shows a positive association between the O blood group and the Rh-negative blood group with bronchial asthma.