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THE cis AB PHENOTYPE IN THREE GENERATIONS OF ONE FAMILY: SEROLOGICAL, ENZYMATIC AND CYTOGENETIC STUDIES
Author(s) -
Sabo Bernice H.,
Bush Miriam,
German J.,
Carne L. R.,
Yates A. D.,
Watkins Winifred M.
Publication year - 1978
Publication title -
international journal of immunogenetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.41
H-Index - 47
eISSN - 1744-313X
pISSN - 1744-3121
DOI - 10.1111/j.1744-313x.1978.tb00634.x
Subject(s) - serology , enzyme , antibody , antigen , galactose , phenotype , gene , biology , microbiology and biotechnology , family studies , galactosyltransferase , genotype , red cell , chemistry , biochemistry , genetics , medicine
SUMMARY The blood from three individuals belonging to consecutive generations of one family were characterized as cis AB on the basis of (a) the serological behaviour of the B antigen on their red cells, (b) the presence of weak anti‐B in their sera and (c) family studies, which unequivocally demonstrated the genotype AB: O for two of the individuals with atypical AB groups. The serological behaviour of the A antigen on the red cells was intermediated between that of normal A 1 and A 2 cell. The B antigen gave weak and variable reactions with naturally occurring antibodies. Treatment of the cis AB red cells with an α‐galactosyltransferase in the serum from an A 1 B individual rendered them agglutinable by the normal range of anti‐B sera, demonstrating that the red cells do not lack precursors for the formation of normal B‐active structures. The cis AB sera all contained relatively strong α‐N‐acetylgalactosaminyl‐transferases which had pH optima of 6.0, characteristic of A 1 gene‐specified enzymes. The affinity of the enzymes for UDP‐galactose, as measured by the apparent Ki, appeared to be greater than that of the A transferases in normal A 1 and A 1 B sera. The B‐gene transferases in the cis AB sera were very weak and were more readily inhibited by UDP‐N‐acetylgalactosamine than were the α‐galactosyltransferases in normal B and AB sera. Both the A ‐ and B ‐transferase activities in the cis AB sera are, therefore, in some ways different from the corresponding enzyme activities in the sera of normal A, B or AB donors. Cytogenetic study of blood lymphocytes from all three individuals showed normal karyotypes. Specifically, the terminal bands of the long arms of the No. 9 chromosomes, to which the ABO:Np‐1: AK‐1 linkage group has been assigned, displayed G bands similar to those in cells from other (normal) individuals examined simultaneously.