"2.7.6 Ael
Under usual conditions Ael cells are not agglutinated
by anti-A or -A,B, although they do bind these anti
bodies, as demonstrated by adsorption and elution
[298,337–339]. Saliva from Ael
secretors contains
H, but no A substance. Serum from Ael individuals
usually contains anti-A1 and may also contain an anti
body that agglutinates A2
cells [337,339]. No A
transferase has been detected in Ael serum or red cell
membranes [232,287–289]. Serum H-transferase is
weaker than that found in A1 or A2 serum [289]. No
example of Ael was found in testing 150000 French
blood donors [283], but fifive were found among
400000 Chinese from Taiwan [328]. Ael appears to be
inherited as a rare gene at the ABO locus [337–339].
As a result of allelic enhancement (Section 2.10.2),
AelB cells may be weakly agglutinated by some mono
clonal anti-A and may resemble B(A) phenotype [340]"
The text above comes from Danels' HUMAN BLOOD GROUPS the second edition, page 36
If we just look at the forward group , we may identify it as type O, but because it has weaker anti-A, we do think it is not a normal reaction ,so we will do further investigation ,and then find out it has weak A antigens. It is important for transfusion and organ transplantation.