Rhesus factor

The rhesus factor is a type of protein that's present on the surface of red blood cells. Most people have this protein, which is called the Rh factor or Rh positive, while some people lack it and are called Rh-negative. There are four common Rh antigens: D, C, c, and E. Having certain combinations of these antigens determines a person's Rh status. For example, a person can be Rh positive if they have any of the D, C, or c antigens, and Rh-negative if they have none of these. #dronyicares