What is P Null Blood Group?
When there are no antigens present in the blood group, it can be called a P null blood group. While there is a common ABO blood group that most people belong to, there are some rare cases of blood groups that still exist. So, what is it that makes these blood groups so rare? Well, a lack of certain antigens that have a high frequency or other common antigens of the blood group tends to make one very rare.
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When 1 out of 1000 people has a particular blood type, it can be considered as a rare type of blood group. One of the most recent findings amongst the rare blood groups is the P null blood group and there are no antigens present in this group. In this case, the phenotype is denoted as ‘p’ and the genotype is denoted as ‘pp’. The people that have the pp genotype will always have P1 and P+ antibodies in their serum. Here, students are going to learn more about this rare blood group which is known as P null.
Characteristics of the Rare Blood Group of P Null
The blood group system of P includes the classification of blood done on the basis of 3 different substances in the blood. These substances are known as the P1, Pk, and P antigens. These antigens are found on the surface of the red blood cells that exist in the body. Some of the antigens can also be seen in the lining of the urinary tract cells. These locations are known as adhesion sites and they tend to house the Escherichia coli bacteria, a rare type of bacteria that leads to problems such as urinary tract infections. The P null group is a part of the P blood group.
The P blood group was discovered in the year 1927. There are certain alleles that are present in the blood group including P, Pk, and P1. The P1 and P antigens are created with the help of the gene that is known as B3GALNT1 or beta-1,3-N-acetyl-galactosaminyltransferase 1. On the other hand, the Pk antigens are created with the help of the gene known as A4GALT or alpha 1,4-galactosyltransferase.
The P blood group consists of 5 different types of phenotypes which are P1, P1k, P2, P2k, and P. The phenotype P was formerly called Tj(a−). The P1 phenotype tends to be the most commonly occurring one in different blood groups and all the three antigens are displayed in this particular phenotype. In the case of the P2 phenotype, there are Pk and P antigens that are present there.
That is why it is known to be the second most common example of the phenotype. On the other hand, the phenotype P1K and P2K, as well as P, aren’t very common in the blood groups. Antibodies that are used against the antigens belonging to the P null phenotype blood group can cause certain transfusion reactions.
Who Founded the P Null Group?
The discovery of the P null blood group took place in the Kasturba Medical College which is a part of the Mangaluru Hospital. According to the facts, a patient was admitted to the Kasturba Medical College and was in immediate need of an urgent blood transfusion. When the sample of the patient’s blood did not end up matching with more than 80 different blood units, that particular sample was sent to the laboratory for further testing. The sample went through a lot of diagnostic tests in order to determine the nature of the blood group that it belonged to.
After the completion of extensive testing, the team working at International Blood Group Reference Laboratory, United Kingdom, where the sample was sent for testing confirmed the rarity of the blood group. They claimed that the blood group belonged to the category of P null and had a phenotype of ‘pp’. This was basically one of the first instances where such a rare group of blood was identified by researchers in any country. In usual cases, most people tend to belong to the ABO blood group or the Rh blood group. However, there are about 200 or more blood groups about which proper information is not provided.
The P null blood group is definitely one of the rarest of the blood groups to have been discovered to this date. The blood group has the phenotype ‘pp’, according to the experts, along with some other rare aspects as well. Here we covered some explanation about the rare blood group of P null.
FAQs on P Null Blood Group
1. What is the P null blood group?
The P null blood group is an extremely rare blood type within the P blood group system. Individuals with this blood group lack all P system antigens (P, P1, and Pk) on their red blood cells. This absence makes it very challenging to find compatible blood for transfusions, as they can only receive blood from other P null donors.
2. What is the genetic basis of the P null phenotype?
The P null phenotype, often denoted as (pp), arises from a specific genetic inheritance. It occurs when an individual inherits two recessive 'p' alleles from their parents. This genetic combination means their body cannot produce the enzymes required to create any of the characteristic antigens of the P blood group system on their red blood cells.
3. What makes the P null blood group clinically significant during a blood transfusion?
The clinical significance of the P null blood group lies in the antibodies present in the plasma. Individuals with P null blood naturally produce a potent antibody called anti-PP1Pk. If they are transfused with blood containing any P-system antigens (like the common P1 or P2 types), this antibody will vigorously attack the donated red blood cells, leading to a severe and potentially fatal hemolytic transfusion reaction.
4. How does the P null blood group differ from the Bombay (hh) blood group?
While both are very rare and pose transfusion challenges, they involve different antigen systems:
- P null Blood Group: This involves the absence of antigens within the P blood group system. These individuals cannot receive blood with P antigens.
- Bombay Blood Group: This is defined by the absence of the H antigen, which is the precursor needed to form A and B antigens. Therefore, they lack A, B, and H antigens.
Essentially, they are rare for different biochemical reasons and are incompatible with each other.
5. Are there other health implications for individuals with the P null blood group?
Yes, beyond transfusion issues, the P null phenotype is associated with specific health risks, particularly in obstetrics. The strong anti-PP1Pk antibodies produced by individuals with this blood type have been linked to an increased incidence of spontaneous abortions, especially during the first trimester of pregnancy, as the antibodies can react against the foetal cells.
6. How was the P null blood group discovered in India?
The P null blood group was notably identified at Kasturba Medical College when a patient required an emergency blood transfusion. The patient's blood sample did not match with over 80 units of blood. This extreme rarity prompted further investigation, and the sample was sent to the International Blood Group Reference Laboratory in the UK. Tests there confirmed it was the rare P null phenotype (pp).
7. What are the common phenotypes in the P blood group system?
The P blood group system primarily consists of two common phenotypes: P1 and P2. The vast majority of the global population falls into one of these two categories. The P null (pp) phenotype is the rare exception, characterised by the complete absence of the antigens found in the P1 and P2 groups.
