Researchers continue to deepen our knowledge of human blood types beyond the familiar ABO and Rh systems. In a major breakthrough, scientists in the UK and Israel identified a new blood group system called MAL, solving a decades‑old mystery that began with a 1972 blood sample lacking a common surface antigen. This discovery — published in the journal Blood after more than 50 years of investigation — helps explain rare variants and improves how clinicians can match blood for safe transfusions.
While type O remains the most common ABO blood type worldwide, it is defined simply by the absence of both A and B antigens on red blood cells. This “lack” affects how the immune system recognizes blood during transfusion and is part of why type O negative red blood cells are often used in emergency situations. Type O’s universal donor status applies specifically to red cells, not plasma, and full compatibility always depends on other antigen systems too.
Scientific studies also explore how blood type relates to health. Research suggests people with type O may have a lower risk of coronary heart disease and stroke compared with other ABO types, potentially due to differences in clotting factors, though lifestyle and genetics play a far larger role in overall health.
At the same time, type O is linked to slightly lower levels of certain clotting proteins, which can increase bleeding tendencies in some medical situations. Other research has found that individuals with type O may face modestly higher risks for certain bleeding complications, illustrating that no blood type is universally “best” or free from health associations.
Scientists emphasize that blood type is just one of many genetic and environmental factors influencing health outcomes. Although type O’s links with disease risk and longevity emerge in population studies, they don’t determine individual health on their own.
In sum, what researchers have uncovered in recent years — including the identification of the MAL blood group and ongoing studies of ABO‑linked health patterns — advances medical science and improves patient care. These findings illustrate the complexity of blood biology and highlight how modern genetics is refining our understanding of blood group diversity.
