A transfusion medicine educator wonders if colleagues would share their opinions (and best references) regarding the molecular and genetic basis for para-Bombay phenotype individuals. One source of confusion to the inquiring educator has been what she believes are conflicting reports in credible publications, including the AABB Technical Manual (13th and 14th editions) which states that para-Bombay phenotype individuals have a nonfunctional H-gene but a normal Se gene and thus will express A, B and H antigens in their plasma and secretions, while the AABB monograph entitled "AABB Blood Group Systems ABH and Lewis (1986)" reports that para-Bombays are all A, B and H NON-secretors. To make matters even more confusing to this educator, the excellent book by Issitt "Applied Blood Groups Serology, 4th edition suggests that para-Bombays may be either non-secretors or secretors! Input from knowlegeable colleagues would be appreciated.

The following responses were received.

ADDENDA April 6, 2003

1. A colleague in Europe is of the opinion that the designation "Para-Bombay" is used for two distinct entities:

• The H-deficient secretor (inactive H-transferase, normal Se-Transferase)
• The H-deficient non-secretor with minimal residual activity of the H-transferase (minimal active H-transferase, inactive Se-Transferase).

The H-deficient secretor is the usual Para-Bombay situation. There are many publications supporting this use of the designation "Para-Bombay", including the first molecular characterization in Kelly R et al., Molecular basis for H blood group deficiency in Bombay (Oh) and para-Bombay individuals. Proc Natl Acad Sci U S A. 1994 Jun 21;91(13)5843-7.

The use of "Para-Bombay" for an H-deficient non-secretor with minimal residual activity is infrequent. A possible reference to this can be found in Geoff Daniels (ed), Human blood groups (2nd edition) Blackwell 2002, page 44.

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Ira A. Shulman, MD
CBBS e-Network Forum Editor & Moderator