Subject: Various 'other' blood groups--Duffy, Kell, Lutheran, Cartwright, etc...

In understand that there are various antigen systems affecting 
blood "type" and I am interested in those antigens and antibodies such as 
Duffy, Kell, Lutheran, Cartwright groups.  Are these antigens on the cells 
as with ABO?  How complex are they (as far as Duffy mixing with other non-
Duffy blood--is there a heterozygote where this wouldn't matter [such as 
AO mixing with an AA person or OO with an AO person, etc.]).  I assume 
they are weaker than the ABO or Rh systems but are  they even 
significant?  Can we tell based on our generic blood type--O+ for 
instance.  And in what circumstances would this be important to know?

THANKS!
Jennifer

Re: Various 'other' blood groups--Duffy, Kell, Lutheran, Cartwright, etc...