Blood Type
Blood type refers to the antigen types present on the surface of blood components, including red blood cells, white blood cells and platelets. Generally speaking, it specifically denotes the unique antigens on the red blood cell membrane. The ABO and Rh blood group systems are the most clinically relevant and well-known classification systems.
ABO Blood Group
The ABO blood group system classifies blood into four types based on the presence or absence of antigen A and antigen B on red blood cell membranes. Type A has only antigen A, Type B has only antigen B, Type AB has both antigens, and Type O has neither. People of different blood types carry distinct antibodies in their serum, but never antibodies against their own red blood cell antigens. For example, type A serum only contains anti-B antibodies. In China, type A, B and O each account for about 30% of the population, while type AB makes up around 10%.
Rh Blood Type
Red blood cells carrying the same antigen as rhesus monkeys are classified as Rh positive, while those without this antigen are Rh negative. Among the Han and most ethnic minorities in China, around 99% are Rh positive, and only about 1% are Rh negative. The Rh blood group system is one of the most complex red blood cell blood classification systems. More than 40 Rh antigens have been identified, among which the D antigen has the strongest antigenicity. Therefore, individuals with the D antigen on red blood cells are defined as Rh positive, and those lacking it are defined as Rh negative.
Scientific Principles of Heredity
If the alleles on somatic cell chromosomes inherited from both parents are identical, the individual is called homozygous; for example, allele A paired with allele A for type A blood. If the inherited alleles are different, the individual is heterozygous; for instance, allele A paired with allele O in some type A individuals. In short, every person has exactly two alleles at each gene locus, one inherited from each parent. Homozygous means the two alleles are the same, while heterozygous means they differ. The combination of the two alleles on a chromosome pair is known as the genotype, such as AA and AO in the examples above. Not all inherited genes are expressed physically. The observable trait that appears is called the phenotype. Both genotypes AA and AO result in the phenotype A, which we commonly refer to as type A blood. Thus, blood type actually refers to the phenotypic expression. The difference between genotype and phenotype arises from dominant and recessive genes. A dominant gene can express its trait in both homozygous and heterozygous states. A recessive gene only shows its trait in the homozygous form and remains unexpressed in heterozygotes. In the ABO blood group system, genes A and B are dominant, while gene O is recessive. For example, one chromosome carrying gene A and the other carrying gene O gives a genotype of AO, with a phenotype of type A instead of type O. Only when both chromosomes carry the O gene can the phenotype of type O blood be expressed.
Blood Type Inheritance Rule Chart
The Blood Type Inheritance Chart, also known as the Blood Type Matching Table, allows you to predict your baby's possible blood type by entering the blood types of you and your partner. It is the most scientific method for blood type testing and matching available.
| Blood Type Inheritance Rules - Blood Type Inheritance Chart | ||
| Parental Blood Type | Possible Blood Types of Offspring | Impossible Blood Types of Offspring |
| O与O | O | A、B、AB |
| A与O | A、O | B、AB |
| A与A | A、O | B、AB |
| A与B | A、B、AB、O | —— |
| A与AB | A、B、AB | O |
| B与O | B、O | A、AB |
| B与B | B、O | A、AB |
| B与AB | A、B、AB | O |
| AB与O | A、B | O、AB |
| AB与AB | A、B、AB | O |
Principle Analysis：
| Composition | Blood Group | |
| Ai | AA | A型 |
| Bi | BB | B型 |
| AB | AB型 | |
| ii | O型 | |
(Note: i represents the recessive gene, and ii corresponds to type O blood. Ai and Bi are heterozygous genotypes. Taking Ai as an example, its phenotype is type A. Among a pair of chromosomes, one carries the dominant A gene and the other carries the recessive O gene. See the scientific principles for details.)
Inheritance Rules of Blood Type
| Parental Blood Types | Possible Combinations | Possible Outcomes | Remarks (Only) | Result | Ratio (For Reference Only) |
| O与O | ii+ii | ii | O | O | 1 |
| A与O | Ai+ii | Ai、ii | A、O | A、O | 3：1 |
| AA+ii | Ai | A | |||
| A与A | Ai+Ai | AA、Ai、ii | A、O | A、O | 15：1 |
| AA+Ai | AA、Ai | A | |||
| AA+AA | AA | A | |||
| Ai+AA | AA、Ai | A | |||
| A与B | AA+BB | AB | AB | AB、A、B、O | 9：3：3：1 |
| Ai+Bi | AB、Ai、Bi、ii | AB、A、B、O | |||
| AA+Bi | AB、Ai | AB、A | |||
| Ai+BB | AB、Bi | AB、B | |||
| A与AB | Ai+AB | AA、AB、Ai、Bi | A、AB、B | A、AB、B | 4：3：1 |
| AA+AB | AA、AB | A、AB | |||
| B与O | BB+ii | Bi | B | B、O | 3：1 |
| Bi+ii | Bi、ii | B、O | |||
| B与B | Bi+Bi | BB、Bi、ii | B、O | B、O | 15：1 |
| BB+Bi | BB.Bi | B | |||
| BB+BB | BB | B | |||
| Bi+BB | BB、Bi | B | |||
| B与AB | Bi+AB | AB、Ai、Bi、BB | A、B、AB | A、AB、B | 1：3：4 |
| BB+AB | AB、BB | AB、B | |||
| AB与O | AB+ii | Ai、Bi | A、B | A、B | 1：1 |
| AB与AB | AB+AB | AA、BB、AB | A、B、AB | A、AB、B | 1：2：1 |
Rh Blood Group System
The Rh blood group system, named after the rhesus macaque, is one of the human blood group systems and is divided into Rh positive and Rh negative. A person is Rh positive, marked as Rh(+), if D antigen exists on red blood cells; otherwise, the person is Rh negative, marked as Rh(-). Most people are Rh positive. The Rh system is perhaps the most complex red blood cell blood group system, second only to the ABO system in clinical importance.
Classification of Rh Blood Group
Differences Between Rh Positive and Rh Negative
The Rh blood group system classifies human blood into Rh positive and Rh negative based on the presence or absence of the Rh factor. The term Rh derives from the first two letters of Rhesus Macaque. In 1940, scientists including Landsteiner discovered Rh antigens on the red blood cells of rhesus macaques and most humans during animal experiments, hence the name. Individuals with Rh agglutinogens on their red blood cells are Rh positive, while those without are Rh negative. This further divides the four major blood groups A, B, O and AB into Rh positive and Rh negative subtypes respectively. With in-depth research, the Rh blood group system is regarded as the most complex red blood cell blood group system. The discovery of the Rh blood group is of great significance for guiding blood transfusion scientifically, improving the laboratory diagnosis of neonatal hemolytic disease and protecting maternal and infant health. According to relevant data, Rh positive blood type accounts for about 99.7% of the Han nationality and most ethnic groups in China, and around 90% in some minority groups. In certain foreign ethnic groups, approximately 85% of people are Rh positive, among whom Rh negative individuals make up about 15% of Caucasians in Europe and America.
People with Rh negative blood cannot receive Rh positive blood, as the antigens in Rh positive blood will stimulate the Rh negative body to produce Rh antibodies. Re-transfusion of Rh positive blood will cause a hemolytic transfusion reaction. However, Rh positive individuals can accept Rh negative blood.
Note: Both Rh and ABO blood groups must be tested before blood transfusion.
Rh Positive Blood
Around 85% of the population has Rh positive blood, which is the most common type. People with Rh positive blood can receive both Rh positive and Rh negative blood of the same type without adverse reactions.
Rh Negative Blood
Known as "panda blood", Rh negative blood is speculated based on cultural archaeology, physiological evolution, ethnic distribution and molecular clock theory to be the blood type of people from the ancient continent of Atlantis. Following a different evolutionary path from the Cro-Magnons, they were Neanderthals who migrated directly from North Africa to Western Europe, quickly occupied Atlantis and established the earliest prehistoric civilization. A massive flood at the end of the ice age over ten thousand years ago destroyed their civilization completely, and some Atlanteans fled to Western Europe. Later, as Cro-Magnons entered Europe and integrated with the remaining Atlanteans, Rh negative blood gradually spread across populations.
Rh- Blood Group
The Rh(-) gene is a recessive gene. If both Rh(+) parents carry the recessive Rh(-) gene and pass it on to their offspring, the child will have Rh(-) blood type. If one parent is Rh(-), the probability of the child being Rh(-) increases; otherwise, the probability decreases.
The distribution of Rh(-) blood varies greatly among races. It accounts for about 15% of Caucasians. In China, the proportion of Rh(-) blood is 5% among ethnic minorities such as the Uyghurs in Xinjiang, nearly 1% among Mongolians, and merely 0.3% among the Han nationality, making it a rare blood type. Considering both the ABO and Rh blood group systems, the chance of finding an AB Rh(-) matched donor among Han people is less than 0.03%, which is extremely rare.
Rh Blood Group Inheritance Chart
Parental Rh(D) Blood Type: Positive + Positive ｜ Offspring Rh(D) Blood Type: Positive / Negative
Parental Rh(D) Blood Type: Positive + Negative ｜ Offspring Rh(D) Blood Type: Positive / Negative
Parental Rh(D) Blood Type: Negative + Negative ｜ Offspring Rh(D) Blood Type: Negative
Note: Rare exceptions such as pathological changes and gene mutations may cause inconsistencies in blood group inheritance between parents and children. The only accurate method for paternity testing is DNA analysis, which directly verifies whether the inheritance of genetic materials conforms to Mendelian inheritance laws.