Scientists are working to grow the rarest blood type in the world in a lab, an effort that could have huge ramifications for medicine. The blood type in question, Rh null, is found in just 50 people ...

An investigation into why blood doesn't always behave as doctors expect has revealed a super-rare mutation in an extremely uncommon variation of blood. Testing more than 544,000 blood samples in a ...

In a routine blood test that turned extraordinary, French scientists have identified the world’s newest and rarest blood group. The sole known carrier is a woman from Guadeloupe whose blood is so ...

As blood banks across the U.S. report dangerously low supplies of O-negative blood (red blood cells), anesthesiologists are calling for increased donation and changes in how hospitals use this ...

Zainab Mughal, a 2-year-old girl from Miami, needs blood transfusions for her cancer treatment but she has a blood type so rare that so far only four donors worldwide have been identified. In August, ...

Two-year-old Zainab Mughal has neuroblastoma, an aggressive form of cancer. In December, we told you about the international search to find some of the rarest blood in the world to help save her life.

A person's blood type is determined by "the presence or absence of certain antigens – substances that can trigger an immune response if they are foreign to the body," according to American Red Cross.

An investigation into why blood doesn't always behave as doctors expect has revealed a super-rare mutation in an extremely uncommon variation of blood. Testing more than 544,000 blood samples in a ...