Vel blood group
... that the Vel blood group was discovered when a patient experienced a severe transfusion reaction, and her blood type was found to be incompatible with all but five out of ten thousand blood donors?
... that the <b id="mwCWQ"><a href="./Vel_blood_group" id="mwCWU" rel="mw:WikiLink" title="Vel blood group">Vel blood group</a></b> was discovered when a patient experienced a severe transfusion reaction, and her blood type was found to be incompatible with all but five out of ten thousand blood donors?