Photo/IllutrationAn image of the proteins of a KANNO-positive individual (green), and a KANNO-negative patient (red), shows they are different in terms of the amino acid (yellow). (Provided by the research team)

The International Society of Blood Transfusion (ISBT) has recognized a new blood group system called KANNO, first identified by scientists in Japan.

The most famous blood group system is the ABO, consisting of the four blood types, A, B, O and AB. But there are many other systems defined by blood components.

It is the first time a blood group system found by Japanese scientists has been recognized by the society.

The KANNO system is the 37th to be recognized by the ISBT, which shares information among professionals to improve the safety of blood transfusion around the world.

Researchers primarily from the National Center for Global Health and Medicine and the Japanese Red Cross Society identified the system.

It consists of KANNO-negative and KANNO-positive groups similar to those in the Rh negative and positive system, according to the team.

Most humans, 99.5 percent, are in the KANNO-positive group.

Transfusing the blood of a group A patient with Rh-positive blood into another group A individual with Rh-negative blood leads to blood clotting and threatens the recipient’s life.

To avoid this, medical centers take samples of the patient's blood before a transfusion and mix it with the donor's blood to see if they clot.

The KANNO category was first identified in 1991 at the Fukushima Medical University Hospital.

When researchers there mixed a patient’s blood sample with a donor’s blood in a test in preparation for transfusion, clotting was reported, although the recipient and donor were designated in the same group under all blood categorization systems then known.

They temporarily named the unknown blood group KANNO-negative after the patient. More than 10 patients have since been confirmed to have KANNO-negative blood.

When the research team conducted a genetic analysis to locate the difference between KANNO-positive and KANNO-negative blood, it found that the KANNO-negative group has an amino acid mutation in a protein gene sequence.

Since KANNO-negative patients are extremely rare, they sometimes need to store their own blood in advance for a transfusion, according to the team.