The DwightTimes

By Journalist of Science Cheryl Magnolia Lavonne Cynn (G11)

At a doctor’s appointment, you may wonder “What is a blood type?” or “How do they decide a blood type?” Blood, though it appears the same to our naked eye, contains microscopic markers called antigens. It is the presence or absence of antigens which determine our blood type, and different antigens can be sorted into something called a “blood group system”.

The most common blood group system is the ABO system. Depending on the presence of A and B antigens in the blood, a person could get one of four types: A (only A antigens), B (only B antigens), AB (both A and B antigens), and O (no antigens). ABO typing is further specified based on the presence of RhD antigens. When red blood cells have RhD antigens, the blood type is positive (A+, B+, AB+, O+). Without RhD antigens, the blood type is negative (A-, B-, AB-, O-). O- blood is crucial for medical emergencies because it’s compatible with every blood type. For this reason, O- blood is called the “universal donor”. (NHS, 2017)

Now, the ABO system isn’t the only one of its kind, there are multiple, lesser known systems you may not have heard about. There is a massive total of 371 antigens, spanning across 48 blood group systems, recognised by the International Society of Blood Transfusion. (ISBT, 2025) The Gwada-negative (officially named PIGZ) blood group system, listed on May 31st 2025, was the most recent addition to the list. The PIGZ system is extraordinarily rare, possessed only by a single woman from Guadeloupe. Every other person in the world is considered Gwada-positive. This makes it extremely difficult, if not impossible, for her to find a compatible donor. (Olsson, 2025)

Though, not all hope is lost for people like her. At Nara Medical University, a group of Japanese scientists led by Hiromi Sakai aim to develop artificial blood compatible with all blood types. To create the artificial blood, hemoglobin (an iron-rich protein used to transport oxygen and carbon dioxide) is extracted from red blood cells. The extracted hemoglobin is enclosed in a shell, creating an artificial, typeless blood cell. Human blood cells last a maximum of 42 days when refrigerated, while these artificial cells can last up to five years. Moreover, the red blood cells used by the research group were recycled to combat blood shortage, sourced from expired donor blood. (Hernon, 2025) This development is hope that life-saving transfusions may one day be possible and accessible to everyone.