donor<unk> , or may self-donate before elective surgery that calls for a<unk>  transfusion. When exposed to<unk> -positive<unk>  through transfusion or pregnancy,<unk> -negative individuals can become sensitized and begin producing an anti-Vel antibody. If they are exposed to<unk> -positive<unk>  again, the anti-Vel antibody can bind to<unk> -positive red<unk>  cells and destroy them, causing hemolysis. Anti-Vel is a particularly dangerous antibody because it is able to activate the complement system, which causes immediate and severe destruction of red<unk>  cells. Therefore, patients with anti-Vel should not be transfused with<unk> -positive<unk> , as it can cause a serious acute hemolytic transfusion reaction. Finding compatible<unk>  for<unk> -negative patients is difficult due to the rarity of this<unk>  type, and it may be necessary to perform autologous<unk>  donation or to contact rare<unk>  banks. Cases of anti-Vel causing hemolytic disease of the newborn (HDN) have been reported, but this is an unusual occurrence. It is hypothesized that anti-Vel associated HDN is rare because the antibody is usually predominantly composed of IgM immunoglobulin, which does not cross the placenta into the fetal circulation. In addition, the expression of<unk>  is very weak on fetal red<unk>  cells – particularly in children who are heterozygous for<unk> . Autoimmune hemolytic anemia (a condition in which patients produce antibodies against antigens on their own red<unk>  cells, leading to hemolysis) involving auto-anti-Vel has been reported.
Vel blood group
Indian blood group system
Hh blood group
Junior blood group system
P1PK blood group system
Rh blood group system
Sid blood group system
Augustine blood group system