A functional AQP1 allele producing a Co(a-b-) phenotype revises and extends the Colton blood group system.

Autor: Arnaud L; National Institute of Blood Transfusion, INTS, Paris, France. larnaud@ints.fr, Helias V, Menanteau C, Peyrard T, Lucien N, Ripoche P, Lapègue R, Pham BN, Le Pennec PY, Moulds JJ, Cartron JP
Jazyk: angličtina
Zdroj: Transfusion [Transfusion] 2010 Oct; Vol. 50 (10), pp. 2106-16. Date of Electronic Publication: 2010 Oct 04.
DOI: 10.1111/j.1537-2995.2010.02687.x
Abstrakt: Background: The Colton blood group system currently comprises three antigens, Co(a) , Co(b) , and Co3. The latter is only absent in the extremely rare individuals of the Colton "null" phenotype, usually referred to as Co(a-b-), which lack the water channel AQP1 that carries the Colton antigens. The discovery of a Co(a-b-) individual with no AQP1 deficiency suggested another molecular basis for the Co(a-b-) phenotype.
Study Design and Methods: Red blood cells were analyzed by stopped-flow light scattering and Western blotting and typed by hemagglutination and flow cytometry. Genotyping by sequencing and polymerase chain reaction-restriction fragment length polymorphism was applied. An expression system for Colton antigens was developed in mammalian cells.
Results: Although Co(a-b-), the proband expressed fully functional AQP1 and had developed a novel Colton alloantibody. Sequencing of AQP1 revealed a homozygous nucleotide change (140A>G) encoding the single-amino-acid substitution Q47R. A second case was identified due to the presence of this novel Colton alloantibody. By generating an expression system for Colton antigens in K-562 cells, the Q47R substitution was shown to inhibit the expression of both Co(a) and Co(b) antigens. Other naturally occurring single-amino-acid substitutions, that is, A45T, P38L, and N192K, were also studied in this Colton antigen expression system.
Conclusions: The Co(a-b-) phenotype can be generated by a functional AQP1 allele, that is, AQP1 140G encoding AQP1 (Q47R) and allowing the development of a novel Colton alloantibody. This study also shows that the Co(b) antigen can be produced by at least two different substitutions at Amino Acid Position 45, that is, A45V and A45T.
(© 2010 American Association of Blood Banks.)
Databáze: MEDLINE
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