During routine ABO-grouping it happens from time to time that the cell grouping and the serum control do not give corresponding results. The factors responsible may be the test sera or test cells, techniques or methods used, deterioration of the sample, or it may be that the intrinsic properties of the blood under test are responsible for the findings. I n the last case, where artificial causes can be excluded, the irregularity may be due t o a weak or undetectable red cell antigen [from A,(6) down t o A, (12, 13), from B, (10) and B, (8) down to the Bombay variety (1, 2)], a positive direct antiglobulin test, the presence of an irregular antibody in the serum, or delay in the formation of antigens or antibodies in the newborn. I n rare cases the cause has been hypo-y-globulinaemia (9), foetomaternal haemorrhage resulting in transient neutralization of the isoagglutinins (4), or chimeras (3, 5, 11).A report of an irregular ABO group follows. Although a number of tests were used to identify it and the findings were reproducible, the classification of the case still remains undecided.
Case HistoryThe case described is that of a male (B. H.), 20 years of age. His parents are not related and he is their only child. He has no apparant malformation, feels well and is a t present doing his National Service. As difficulties arose in ABO-grouping him, a blood sample was sent t o The Blood Group Reference Laboratory for further investigations.B. H. was later bled and retested 4 times in the laboratory over a period of 12 months.
Serological InvestigationsRoutine examination of the blood (on slides at room temperature) showed no agglutination of the red cells by anti-A, anti-B, or anti-AB (group 0) serum. The serum showed a normal agglutination of B cells, but no agglutination of A, cells.
