Para-Bombay B phenotype: a rare ABH blood group variant at tertiary care hospital, Gwalior India

Background: The H antigen is the precursor substance for A and B antigens formation on red blood cells of an individual and absence of it is termed as H deficient phenotype. If H antigen is absent on both RBCs and secretions, and then the resulting blood group is a Classical Bombay phenotype with anti-H antibodies in their serum. If H antigen are absent on RBCs and present in secretions and plasma, the resulting blood group is Para-Bombay phenotype. Genetically Para-Bombay’s lack an active H gene (genotype is hh) but carry at least one Se gene (Secretor gene). Para-Bombay or red blood cell (RBC) H negative secretor individuals may or may not have anti-H in their serum. In both cases routine blood grouping is O. Case Report: Blood sample of 24-year-old female is submitting in blood bank, resulting her routine grouping O RhD positive. Complete blood grouping by Gel technology revels her forward grouping is Oh and reverse grouping B. Patient is secretor for B and H antigens. Absorption and elusion test is negative. Family grouping was also done to find out compatible blood and her family genesis. Conclusion: Patient blood group is Para-Bombay B. Complete blood grouping (Forward and reverse) as well as saliva grouping and absorption /elusion test is advisable when there is a discrepancy in ABH grouping.