Background: The rare Bombay phenotype is usually due to a primary genetic defect in an alpha-2- or alpha-4-fucosyltransferase. The present study was done to investigate a patient with normal transferases, who exhibits the Bombay phenotype.
Case report: Red cells of the patient, his parents, and siblings were phenotyped for A, B, and H antigens. The presence of B, H, and Le transferases in serum and saliva was measured.
Results: The parents and siblings were all group B, Le(a-b-). The propositus was typed as Oh, Le(a-b-). His serum contained anti-A, anti-B, and anti-H. Normal levels of B, H, and Le transferases were found in all family members including the patient.
Conclusion: In an unusual case, a person has the Bombay phenotype, but normal levels of transferases in serum and saliva. A general defect in fucose metabolism seems to be the primary abnormality in this case.