Blood type refers to the classification of blood based on the presence or absence of certain antigens on the surface of red blood cells. The two main systems used to categorize blood types are the ABO system and the Rh factor.
Blood Types (ABO Blood Group System)
- Type A: Has A antigens on the surface of red blood cells.
- Type B: Has B antigens on the surface of red blood cells.
- Type AB: Has both A and B antigens on the surface of red blood cells.
- Type O: Has no A or B antigens on the surface of red blood cells.
Blood type is determined by the presence or absence of specific antigens on the surface of red blood cells, and the inheritance of blood type is governed by alleles. The two main blood type systems are the ABO system and the Rh factor.
Alleles
The ABO system involves three main alleles: A, B, and O.
Individuals inherit one allele from each parent, resulting in the following possible combinations:
- AA or AO: Blood type A
- BB or BO: Blood type B
- AB: Blood type AB
- OO: Blood type O
Codominance and Dominance
A and B alleles are codominant, meaning they can both express themselves when present together.
O is recessive to A and B, meaning it is only expressed when no A or B alleles are present.
Inheritance
A child inherits one allele from each parent, and the combination of these alleles determines the child's blood type.
The inheritance follows Mendelian genetics, with codominance in the ABO system and dominance in the Rh factor.
Understanding blood type alleles is crucial in predicting potential blood types in offspring, ensuring compatibility in blood transfusions, and addressing issues related to Rh incompatibility during pregnancy.
On our website you can find out the volume of blood in the body.
What is Rh factor
The Rh factor, also known as the Rhesus factor, is a protein that can be present on the surface of red blood cells. The two main Rh factor options are Rh-positive (+) and Rh-negative (-). The presence or absence of the Rh factor is an important component of blood typing, often denoted as part of the ABO and Rh blood group system.
Here's a brief explanation of Rh factor:
Rh-Positive (+):
If a person's red blood cells have the Rh antigen, they are considered Rh-positive. Approximately 85% of the world's population is Rh-positive.
Rh-Negative (-):
If a person's red blood cells lack the Rh antigen, they are classified as Rh-negative. Around 15% of the world's population is Rh-negative.
If Both Parents are Rh-Positive - the baby is likely to be Rh-positive.
If One Parent is Rh-Negative and the Other is Rh-Positive - the baby has a chance of being Rh-positive. The Rh-positive gene is dominant, so if the Rh-negative parent contributes an Rh-positive allele, the baby will be Rh-positive.
If Both Parents are Rh-Negative - the baby will be Rh-negative.
- Type A can donate to A and AB.
- Type B can donate to B and AB.
- Type AB can donate to AB.
- Type O can donate to A, B, AB, and O.
- Rh-positive individuals can receive blood from Rh-positive or Rh-negative donors.
- Rh-negative individuals can receive blood only from Rh-negative donors.
Rh factor of the baby
The Rh factor of the baby is determined by the combination of Rh factors inherited from the parents. The Rh factor, or Rhesus factor, can be either positive (+) or negative (-). Here's a summary based on the Rh factor of the parents:
To illustrate with an example:
If the mother is Rh-positive (e.g., A+) and the father is Rh-negative (e.g., B-), there is a chance the baby will be Rh-positive because the Rh-positive gene is dominant.
Remember that these are probabilities, and the actual outcome depends on the specific alleles inherited from each parent during fertilization. If you have the Rh factor of both parents, you can make an educated prediction based on the inheritance patterns described above. For precise information, medical blood typing or DNA testing is necessary.
Compatible blood types
Blood transfusion compatibility is crucial to avoid adverse reactions between the donor's blood and the recipient's blood. The compatibility is determined by the ABO blood group and the Rh factor. Here's a general table illustrating blood transfusion compatibility:
| Donor's Blood Type | Can Donate to Recipient's Blood Type |
|---|---|
| A- | A-, AB- |
| A+ | A+, A-, AB+, AB- |
| B- | B-, AB- |
| B+ | B+, B-, AB+, AB- |
| AB- | AB- |
| AB+ | AB+, AB- |
| O- | O-, A-, B-, AB- |
| O+ | O+, O-, A+, A-, B+, B-, AB+, AB- |
Explanation:
ABO Blood Group Compatibility:
Rh Factor Compatibility:
Universal Donors and Recipients:
O- is considered the universal blood donor as it can be given to individuals with any blood type.
AB+ is considered the universal blood recipient as individuals with this blood type can receive blood from donors of any ABO and Rh type.
It's important to note that this is a general guide, and in specific medical situations, additional considerations may be necessary. Cross-matching and compatibility testing are always performed before blood transfusions to ensure a safe match between the donor and the recipient.
Blood Type Percentages in the US
| Blood Type / Rh | Percentage |
|---|---|
| O positive (O Rh+) | 38% |
| A positive (A Rh+) | 34% |
| B positive (B Rh+) | 9% |
| O negative(O Rh-) | 7% |
| A negative(A Rh-) | 6% |
| AB positive (AB Rh+) | 3% |
| B negative (B Rh-) | 2% |
| AB negative(AB Rh-) | 1% |
Importance in Medicine
Understanding the Rh factor is crucial in medical contexts, particularly during pregnancy and blood transfusions. Incompatibility between the Rh factor of a pregnant woman and her baby can lead to Rh incompatibility issues, potentially causing hemolytic disease of the newborn (HDN).
In blood transfusions, it is essential to match the Rh factor between the donor and the recipient to prevent adverse reactions. For example, an Rh-negative person receiving Rh-positive blood can lead to an immune response, potentially causing serious complications.
Knowing a person's Rh factor is part of their complete blood type, which is expressed as a combination of the ABO blood group and the Rh factor (e.g., A+, B-, AB+).
Based on research by