Molecular genetic basis of the histo-blood group ABO system
The histo-blood group ABO, the major human alloantigen system, involves three carbohydrate antigens (ABH). A, B and AB individuals express glycosyltransferase activities converting the H antigen into A or B antigens, whereas 0(H) individuals lack such activity. Here we present a molecular basis for the ABO genotypes. The A and B genes differ in a few single-base substitutions, changing four amino-acid residues that may cause differences in A and B transferase specificity. A critical single-base deletion was found in the 0 gene, which results in an entirely different, inactive protein incapable of modifying the H antigen. 
Blood group isoantibody stimulation in man by feeding blood group-active bacteria
It was investigated whether or not the human blood group isoantibodies A and B could be induced by immunogenic stimuli via natural routes with a kind of antigenic substance to which all humans are commonly exposed, or if the appearance of these antibodies is independent of antigenic stimuli as has long been believed.
Escherichia coli O86, which possess high human blood group B and faint A activity in vitro, were fed to healthy humans and those with intestinal disorders. 80% of the sick individuals of blood group O and A responded with a significant rise of anti-B antibodies which was frequently de novo in infants; significant increase of anti-A isoantibodies among blood group O individuals was less frequent. Over one-third of the healthy individuals also had a significant isoantibody increase. Intestinal lesions favor isoantibody stimulation by intestinal bacteria; this view was supported by the study of control infants. Persons of blood group A responded more frequently with anti-B and anti-E. coli O86 antibody production than those of blood group O. Isoantibody increase was accompanied with antibody rise against E. coli O86. Inhalation of E. coli O86 or blood group AH(O)-specific hog mucin also evoked isoantibodies.
The induced isoantibodies were specifically inhibited by small amounts of human blood group substances. E. coli O86-induced anti-blood group antibodies in germ-free chickens and preexisting blood group antibodies in ordinary chickens were neutralized by intravenous injection of E. coli O86 lipopolysaccharide.
This study demonstrates that human isoantibodies A and B are readily elicited via physiological routes, by blood group-active E. coli, provided the genetically determined apparatus of the host is responsive. Antibodies against a person’s own blood group were not formed. Interpretation of these results permits some careful generalizations as to the origin of so-called natural antibodies. 
The effect of ABO blood group on the diagnosis of von Willebrand disease
In order to firmly establish a normal range for von Willebrand factor antigen (vWF:Ag), we determined plasma vWF:Ag concentrations in 1,117 volunteer blood donors by quantitative immunoelectrophoresis. The presence of the ABO blood group has a significant influence on vWF:Ag values; individuals with blood group O had the lowest mean vWF:Ag level (74.8 U/dL), followed by group A (105.9 U/dL), then group B (116.9 U/dL), and finally group AB (123.3 U/dL). Multiple regression analysis revealed that age significantly correlated with vWF:Ag levels in each blood group. We then performed reverse ABO typing on stored plasma from 142 patients with the diagnosis of von Willebrand disease (vWd). Of 114 patients with type I vWd, blood group O was found in 88 (77%), group A in 21 (18%), group B in 5 (4%), and group AB in none (0%), whereas the frequency of these blood groups in the normal population is significantly different (45%, 45%, 7% and 3%, respectively) (P less than .001). Patients with type II or III vWd had ABO blood group frequencies that were not different from the expected distribution. There may be a subset of symptomatic vWd patients with decreased concentrations of structurally normal vWf (vWd, type I) on the basis of blood group O. Some individuals of blood group AB with a genetic defect of vWF may have the diagnosis overlooked because vWF levels are elevated due to blood type. 
ABO Blood Groups and Malaria Parasitaemia in Outpatients of BMSH Port Harcourt, Rivers State
A cross – sectional study was conducted to investigate the relationship between ABO blood groups and malaria parasitaemia in Port Harcourt, Rivers State, Nigeria. Thick and thin films made from venous blood samples collected from 1000 consenting outpatient study subjects, were stained with 10% Giemsa stains and viewed microscopically using oil immersion objective to detect malaria parasites following standard parasitological techniques. ABO blood group typing with monoclonal Antisera A, B and D was carried out using agglutination technique. An overall malaria prevalence of 32% was observed among the study subjects irrespective of blood groups. Blood groups A and O had higher malaria prevalence rates of 38% and 33% respectively while blood group AB had the least malaria prevalence rate of 13% (P<0.05). Malaria parasite density levels >1000 parasites/µL in relation to ABO blood groups showed a higher prevalence in blood group A and least prevalence in blood group O with rates of 29% and 3% respectively (P<0.05). This study showed that individuals with blood group O were susceptible to contracting uncomplicated malaria infections but had a high resistance to developing severe malaria parasitemia compared to individuals with blood groups A, B and AB. Malaria control strategies should be directed equally at individuals with the different ABO blood groups because more research is required to fully understand the relationship between ABO blood groups and malaria parasitemia. 
Blood Group Phenotype Frequencies in Blood Donors in the Northeast of Democratic Republic of Congo
Background and Aims: To know blood group antigen frequencies in a population has various benefits as the assessing risk of alloimmunization, the providing antigen-negative compatible blood to patients with multiples antibodies and the development of a donor data bank for the preparation of indigenous cell panels. The aims of this study is to determine the frequencies of the ABO, Rh and Kell antigens in the blood donors in Kisangani, in the northeast region of Democratic Republic of Congo.
Materials and Methods: Blood samples from 252 volunteer blood donors coming to the Blood Transfusion Provincial Center at Kisangani in 2015 were typed by serologic test for ABO, Rh (D, C, E, c, e) and K antigens.
Results: For the 252 blood donors, the most frequent phenotype in the ABO blood group, was O (47.6%) followed by A (30.6%), B (17.1%) and AB (4.1%). If combined ABO and Rh blood groups, O positive was most frequent, followed by A positive, B positive, AB positive, O negative and A negative respectively. In the Rh system, the c antigen was the most frequent (98.8%), followed by e antigen (97.6%), D antigens (96.42%), C antigen (15.9%) and E antigen (13.9%). Among ten phenotypes identified in the Rh system, the phenotype R0r was the most frequently encountered (71.03%). In the Kell system, 100% of donors were K-k+.
Conclusion: Although the Africa specificities for the most immunogenic antigens and the context of limited resources, it is important for better care of patients to improve tests as phenotyping red cells. 
 Yamamoto, F.I., Clausen, H., White, T., Marken, J. and Hakomori, S.I., 1990. Molecular genetic basis of the histo-blood group ABO system. Nature, 345(6272), pp.229-233.
 Springer, G.F. and Horton, R.E., 1969. Blood group isoantibody stimulation in man by feeding blood group-active bacteria. The Journal of clinical investigation, 48(7), pp.1280-1291.
 Gill, J.C., Endres-Brooks, J., Bauer, P.J., Marks, W.J. and Montgomery, R.R., 1987. The effect of ABO blood group on the diagnosis of von Willebrand disease.
 Wogu, M. N., Nduka, F. O. and Nzeako, S. O. (2016) “ABO Blood Groups and Malaria Parasitaemia in Outpatients of BMSH Port Harcourt, Rivers State”, Annual Research & Review in Biology, 11(3), pp. 1-4. doi: 10.9734/ARRB/2016/29928.
 Agasa Salomon, B., Mango Bernard, M., Bome Lucien, B., Basandja Jacques, O., Kombi Paul, K. and Tshilumba Charles, K. (2017) “Blood Group Phenotype Frequencies in Blood Donors in the Northeast of Democratic Republic of Congo”, International Blood Research & Reviews, 7(2), pp. 1-5. doi: 10.9734/IBRR/2017/33385.