Biochemical, Serological and Family Studies in Individuals with Cis AB Phenotypes

Abstract

Pedigree studies and serological characterization of three cis AB families are presented. Serums of these persons exhibit strongly reduced activities of A genespecified α-N-acetylgalactosaminyltransferase and only trace activities of B gene-dependent α-galactosyltransferase.

First report of Cis-AB inheritance from North India

“…Only weak non-auto anti-B antibodies have been reported in some earlier studies (Seyfried et al 1964, Madsen et al 1968, Pacuszka et al 1975. Hence our cis-AB case appears to be different than earlier reported cases in the literature.…”

Unusual Inheritance in the ABO Blood Group System: A Group O Child from A Group A(2)B Mother

“…1). However, if this is the case, the A and B antigens of the family have dif ferent characteristics from the well-docu mented cases we found in the literature [5,14,15,18]. All of them, as well as the Japa nese families referred to by Race and Sanger [16], have weak B antigens and some anti-B activity in their sera, which is not the case with this infant's mother.…”

“…Bernstein [3] formulated his threeallele theory in 1924, which was later ex panded to include allelic subgroups of A and B. This has generally been considered valid, however, it does not explain certain cases observed since then.Several families have been reported [5,[14][15][16]18] with A and B antigens trans mitted by the same chromosome (c«-AB). Boettcher [4] offered an explanation for this unexpected finding by proposing that the ABO blood group antigens are coded by a complex locus in which crossing-over can occur between the A and B subunits.…”

Weak A Phenotypes Possibly Caused by Mutation

“…serum samples were run on adjacent lanes of paper chromatograms. A low A transferase activ ity in the serum of Jan. L. is most likely due to the action of the B transferase [11], Using our standard technique we have also observed occasional low incorporation of Nacetylgalactosamine from UDP-[14C] A-acetylgalactosamine to 2'fucosyllactose with blood group B serum samples [6], The absence of the A transferase activity in the sera of Jer., Jan. and Raf.L. should not disprove our characterization of the weak A phenotypes in the L. family as Ay, since most basic data on the subject were published before the A-, B-, and //-gene-specified enzymes were discovered.…”

“…We favor a mutation of the A allele as the most likely cause of the phenotype. Activities of the serum .4-gene-specified transferase were not detected in any of the 3 family members with the A, phenotypes.tose as the acceptor [5,6]. The H transferase activity of serum was determined by the method of Chester et al [7] using phenylß-Dgalactoside as the acceptor.…”