Our blood contains various components, including red blood cells, which carry oxygen throughout the body. The surface of these red blood cells is coated with specific protein and carbohydrate molecules called antigens. These antigens act as unique identification markers, determining an individual’s blood group. While many are familiar with the common ABO and Rh blood groups, the scientific community continues to uncover additional blood group systems, expanding our understanding of human biological diversity.
What Defines a New Blood Group
A new blood group system is formally recognized based on inherited antigens that are distinct from all previously identified systems. Each blood group system is defined by a single gene or a cluster of closely linked genes that determine the presence or absence of specific antigens on red blood cells. Antibodies, which are proteins found in blood plasma, are formed by the immune system in response to foreign antigens. For instance, individuals with type A blood possess A antigens and anti-B antibodies in their plasma.
Genetic variations lead to the unique structures of these antigens. Blood group antigens are genetically coded and can be composed of carbohydrates or proteins. The genes responsible for these antigens are located on specific chromosomes, and their inheritance patterns are strict. The International Society of Blood Transfusion (ISBT) recognizes 44 distinct blood group systems, each with its own set of antigens.
Uncovering Novel Blood Groups
The discovery of new blood groups often begins with unusual reactions observed during routine blood typing or cross-matching procedures. Standard serological tests, which rely on the visible clumping of red blood cells in the presence of specific antibodies, can yield unexpected results, signaling the potential presence of a novel antigen. While these traditional methods are common, they can be limited in detecting rare or weakly expressed antigens.
Genetic sequencing plays a significant role in pinpointing the exact molecular basis of these new antigens. Next-generation sequencing (NGS) technologies, such as whole-exome sequencing (WES), allow for evaluating genetic changes, including mutations and gene rearrangements. This molecular approach can identify rare blood types even when specific antibodies are not yet known. For example, the recently discovered Er blood group system involved investigating three known antigens that did not fit into any existing system. Researchers used DNA sequencing and gene-editing techniques to establish their genetic background.
Importance in Health and Medicine
The discovery of new blood groups impacts transfusion safety. Mismatches between donor and recipient blood types can trigger severe immune reactions, which may be life-threatening. Understanding these newly identified systems allows for the development of specialized diagnostic tests to identify individuals with rare blood types, ensuring they receive compatible transfusions. This is particularly important for patients who require frequent transfusions or those who have developed antibodies against common antigens.
Beyond transfusion medicine, uncovering new blood groups contributes to a deeper understanding of human genetic diversity. The variability of blood group antigens reflects differences across populations, influenced by geographical and ethnic factors. This knowledge can also offer insights into potential links between specific blood group antigens and susceptibility or resistance to certain diseases. For instance, the Piezo1 protein, which carries the Er blood group antigens, is known to play roles in various diseases. Further research into these connections can advance our understanding of human health.