An Israeli family with six cisAB members: serologic and enzymatic studies.
BACKGROUND
The cisAB blood type is a rare phenomenon in which both the A and B blood types are inherited from a single parent. Several forms of this phenotype have been characterized that differ with respect to serologic reactions and the activities of the gene-encoded blood group A and B transferases.


METHODS
The cisAB blood type was suspected when a baby typed as blood group O was born to a mother whose blood group was AB. Family studies revealed four generations in whom the pattern of inheritance could be explained only by the inheritance of the cisAB genotype. Blood and saliva samples from the family were tested serologically and assayed for the relevant glycosyltransferases. Samples suitable for DNA analysis were not available.


RESULTS
Six family members were shown serologically to be of the cisAB type. The A and B transferases in the sera of these individuals were 20 to 35 and 25 to 50 percent of those obtained for A and B individuals, respectively. The enzymic characteristics of the A and B transferases were determined. The A transferase in the sera of the cisAB persons did not bind to agarose beads.


CONCLUSIONS
The family described carries the cisAB gene, which encodes production of A and B transferases that differ from those of "normal" A, AB, and B controls. This variant has properties that are distinctly different from those described in other reports.
Bennett
M
M
Department of Haematology, Afula Hospital, Israel.
Levene
C
C
Greenwell
P
P
D000017:ABO Blood-Group System / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D000327:Adsorption; D002412:Cations; D004912:Erythrocytes / Q000276:immunology; D005192:Family Health; D016695:Glycosyltransferases / Q000737:chemistry / Q000493:pharmacokinetics; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007519:Isoantigens / Q000032:analysis; D007557:Israel; D010375:Pedigree; D012685:Sepharose; D013379:Substrate Specificity / Q000502:physiology
D000017:ABO Blood-Group System; D002412:Cations; D007519:Isoantigens; D012685:Sepharose; D016695:Glycosyltransferases