Indian J Med Res. 2014 Jan;139(1):105-11.

Molecular genotyping of ABO blood groups in some population groups from India.

Ray S, Gorakshakar AC1, Vasantha K, Nadkarni A, Italia Y, Ghosh K.
  • 1National Institute of Immunohaematology (ICMR), Mumbai, India.



BACKGROUND & OBJECTIVES: Indian population is characterized by the presence of various castes and tribal groups. Various genetic polymorphisms have been used to differentiate among these groups. Amongst these, the ABO blood group system has been extensively studied. There is no information on molecular genotyping of ABO blood groups from India. Therefore, the main objective of this study was to characterize the common A, B and O alleles by molecular analysis in some Indian population groups.

METHODS: One hundred samples from the mixed population from Mumbai, 101 samples from the Dhodia tribe and 100 samples from the Parsi community were included in this study. Initially, the samples were phenotyped by standard serologic techniques. PCR followed by single strand conformational polymorphsim (SSCP) was used for molecular ABO genotyping. Samples showing atypical SSCP patterns were further analysed by DNA sequencing to characterize rare alleles.

RESULTS: Seven common ABO alleles with 19 different genotypes were found in the mixed population. The Dhodias showed 12 different ABO genotypes and the Parsis revealed 15 different ABO genotypes with six common ABO alleles identified in each of them. Two rare alleles were also identified.

INTERPRETATION & CONCLUSIONS: This study reports the distribution of molecular genotypes of ABO alleles among some population groups from India. Considering the extremely heterogeneous nature of the Indian population, in terms of various genotype markers like blood groups, red cell enzymes, etc., many more ABO alleles are likely to be encountered.

PMID: 24604045



The expression of ABO system antigens is influenced by the inheritance and expression of H(FUT1) and Se(FUT2) genes, located on chromosome 19q13.3. The FUT1 gene encodes for α-2-L-fucosyltransferase which adds L-fucose on type 2 chains on RBCs while the FUT2 gene encodes for fucosyltransferase that is expressed in body secretions. Expression of ABO antigens depends on inheritance of at least one H gene (HH/Hh) and Se gene (SeSe/Sese).

Individuals with ‘Bombay’ phenotype inherit the recessive alleles hh and sese in homozygous state and hence cannot synthesize the precursor H antigen. Hence, their RBCs lack the H antigen (precursor of A and B antigen) on their red cells and H substance is also absent in secretions. As a result even though their ABO genes are functional, these individuals cannot synthesize the ABO antigens. Therefore, to determine the ABO type of a Bombay phenotype individual Molecular methods are required as it is not possible to determine serologically. The above mentioned technique is extended to study the ABO alleles of nineteen Bombay phenotype individuals. The ABO genotypes determined among these individuals were: A102O01 (1), A102O03 (1), A102A102 (1), B101O02 (6), A101A102 (1), O01O02 (1), A101O02 (2), B101O03 (2), B101B101 (2), A101B101 (1), A101O01 (1). No new ABO variant allele was found in these cases. The genotyping results were concordant with family studies in cases where ABO blood groups of the family members were known. Figure 1 shows a typical pedigree of a family where one of the siblings is Bombay phenotype and blood groups of the parents was not known. However the ABO genotype of the propositus was determined by PCR-SSCP as AIVO1. This is the first report of detecting the ABO genotype of Bombay phenotype individuals without analyzing the ABO status of the parents.


Figure 1: Typical pedigree diagram of a family of a Bombay phenotype individual.


Tumor progression is often associated with altered glycosylation of cell surface proteins and lipids related to the ABO and Lewis blood group antigens. A relative down-regulation of the glycosyltransferase that is involved in the biosynthesis of A and B antigens is seen in oral carcinomas in association with tumor development. It has been showed that A allelic loss and hypermethylation in the promoter region of the ABO gene is significantly correlated with reduction of A antigen expression in transitional cell carcinoma (TCC), while the expression of the A antigen is maintained in concomitant dysplasia or normal urothelium, suggesting that loss of the ABO gene and/or its promoter hypermethylation is a specific marker for TCC. The events leading to loss of A transferase activity are related, in some instances, to loss of heterozygosity (LOH) involving chromosome 9q34, which is the locus for the ABO gene. The weakening of ABO antigens may be due to inactivation of A and/or B transferases or inactivation of the the H transferase. Therefore serologically many times discrepancy in forward and reverse typing of cancer patients is observed. Knowing the association of ABO type with cancer, to get information about the correct ABO genotype of the patient which can be helpful for transfusion, we genotyped the ABO status of twenty five pateints with cancer (7CML and 18ALL) using PCR-SSCP as shown in Figure 2.



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Figure 2: ABO genotyping using PCR-SSCP in cancer patients.

Lane 1, 4: A102A102; Lane 2, 3, 5, 9, 10: O01O02; Lane 6: A101O02; Lane 7:A201B101; Lane 8: O03O03; Lane 11: 279bp fragment control, Lane 12: 192bp fragment control; Lane 13: 165bp fragment control




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