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Introduction: ABO Blood group system was discovered by Karl Landsteiner in the year 1900 who classified the blood groups into A,B,AB and O on the basis of the presence or absence of the antigens A and B on the cell surface of Red blood cells. Further ,in the year 1911, Von Dungern and Hirszfeld divided the group A into A1 and A2 hence total of six blood groups A1,A2,B,A1B,A2B,O. Aim of the study is to find out the frequency of subgroups of A and AB Blood groups and its importance in transfusion practice. Methods: A total of 5594 blood donors' samples were collected in a one-year period who came to donate blood. Blood grouping was done by the conventional tube method both forward and reverse grouping. Sub grouping of A and AB was done by using the commercially available Lectin Anti A1 (Tulip diagnostics, Goa ,India). Group A red blood cells which agglutinate with Anti A1 lectin are classified as subgroup A1,whereas which do not agglutinate are classified as A2. Result: Out of total 5594 blood donors, 1354 belonged to group A and 413 constituted group AB. The percentage of A1 amongst the A blood group is 93.94% (1272) and A2 is 6.056 (82). The percentage of A1 amongst the AB blood group is 91.04% (376) and A2 is 8.95% (37). Conclusion: The frequency of A1 subgroup is more in comparison to A2 in both A and AB blood groups amongst the blood donors. Identification and recording of subgroups is important in blood bank in respect to blood group discrepancy, blood transfusion reactions as well as Organ transplantation. [ABSTRACT FROM AUTHOR]

The number of original articles published in Indian economic history shows a boom in the 1980s ending in a recession from the 1990s. The paper surveys the evolution of the field and explores the reasons behind these tendencies. It concludes that the trends reflect shifts in the popularity of archives-based research on economic issues among historians in India. Following on from a rise in the 1980s, in the last 20 years, cultural history crowded out economic history, and debates about the process of long-term economic change became rare. More recently, the link between comparative economic growth and Indian history has strengthened, leading to a modest revival. [ABSTRACT FROM PUBLISHER]

Background: The heterogeneity of A and B alleles results in weak variants of these antigens. Subgroups of A differ from each other quantitatively and qualitatively. The expected frequencies of A₁ and A₂ subtypes will be in Hardy-Weinberg equilibrium for the Mendelian inheritance of the allelic A₁ and A₂ genes. The frequency of A subgroups in the population from south India is not known. The aim of our study was to study the frequency of A subtypes and the prevalence of anti-A₁ antibody among this population., Methods: Over a period of 3 years, patients' blood group was typed using a standard tube technique. Anti-A₁ lectin studies were done for all patients with groups A and AB. Based on serological reactivity the samples were classified into A₁/A₁B, A₂/A₂B and weak A subgroups. The prevalence of A subgroups was determined. The significance of differences in proportions was analysed using the chi-square test., Results: A total of 40,113 patients' samples were typed for ABO, Rh group and A subgroups in our blood bank attached to a tertiary care hospital. Among 10,325 group A samples, 98.14% classified as A₁, 1.07% as A₂, and 0.01% as weak A; the remaining group A samples were from neonates and reacted poorly with anti A₁-lectin. The majority of AB samples (n=2,667) were of A₁B type (89.28%). However, the proportion of A₂B (8.99%) among AB samples was significantly higher than that of A(2) in group A samples (p < 0.0001). The prevalence of anti-A(1) antibodies among A₂ and A₂B samples was 1.8% and 3.75%, respectively, and none of them showed reactivity at 37°C., Conclusion: The results of our study show a significantly higher proportion of A₂B subtypes than A₂ subgroups. A similar imbalance is seen in blacks and Japanese. The incidence of anti-A₁ antibodies is also higher among A₂B patients.