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Blood Compatibility and Plasma Compatibility – What is the Difference?

Blood Compatibility and Plasma Compatibility – What is the Difference?

To understand the compatibility, it is important that we know the bases of ABO blood grouping system. It is based on the presence of specific antigen on red blood cells of an individual.

Table 1 shows the antigens present on red blood cells and antibodies presents in plasma for each blood group.

Table 1. Antigens and Antibodies Present for Each Blood Group

Blood Group Ag Present on RBC ABO Abs Present in Plasma
O No Ag Anti A and anti B
A Ag A Anti B
B Ag B Anti A
AB Ag A and Ag B No Abs
Rh+ Rh D No Abs
Rh- No Ag No Abs

In case of Rh + or Rh– there will be no Abs present naturally in plasma because Rh Abs are developed only after an individual is exposed to Rh D antigen.

Now based on this we can differentiate the compatibility for red blood cell type and plasma type. Keep the above table as reference to understand the compatibility.

During transfusion it is preferable for a patient to receive blood and plasma of the same ABO and RhD group but if the required type is not available based on compatibility they may be given alternative type as shown in table 2.

Table 2. Blood Compatibility and Plasma Compatibility for Each Blood Group

Recipient Blood Type Donor RBC Donor Whole Blood

(RBC + Plasma)

 Donor Plasma
A+ A+, A-, O+, O- A+ A- A+, A-, AB+, AB-
A- A-, O- A- A+, A-, AB+, AB-
B+ B+, B-, O+, O- B+, B- B+, B-, AB+, AB-
B- B-, O- B- B+, B-, AB+, AB-
O+ O+, O- O+, O- A+, A-, B+, B-, O+, O-, AB+, AB-
O- O- O- A+, A-, B+, B-, O+, O-, AB+, AB-
AB+ A+, A-, B+, B-, O+, O-, AB+, AB- AB+, AB- AB+, AB-
AB- AB-, A-, B-, O- AB- AB+, AB-

When it comes to blood transfusion, it can be either only red cells or blood as a whole. So if we are talking about RBC, we need to consider only Ags from donor but when we are talking about whole blood since it has both RBC and plasma we need to consider both Ags and Abs from donor. In case of plasma we need to consider only Abs from donor because plasma doesn’t have RBC and so no Ags.

As shown in table 2, plasma from blood group AB can be given to blood group O. But when it comes to blood as a whole because of present of Ags on RBC, O type cannot accept red blood cells or blood as whole from any other blood type other than blood group O.

Blood group A and B type individuals can accept plasma from AB individuals because blood group AB type will not have any Abs in their plasma.

Blood group AB type can accept plasma from only AB type because it is the only plasma without anti A and anti B Abs in it.

Rh- individual can accept plasma from Rh+ individual because there are no anti Rh antibodies present naturally in plasma.

In blood transfusion and to be specific for red cell transfusion, AB is universal acceptor and O is universal donor.

But in plasma transfusion, AB is universal donor and O is universal acceptor.

I hope this helps 🙂

Watch a video on this topic here.

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Pseudo-dominance – Recessive Allele Mimicking Dominant Pattern

Pseudo-dominance – Recessive Allele Mimicking Dominant Pattern

Pseudo = false. Here it is pseudodominance that means it is false dominance.

Pseudodominance: is a condition where a recessive allele mimics the pattern of a dominant allele. 

To understand pseudodominance let’s start with the concept of dominant and recessive allele. In humans, since we are diploid organism we have two copies of every gene i.e. we have two alleles for every gene. And these alleles can be dominant or recessive. For a dominant allele to be expressed only one copy is enough. A dominant allele gets expressed even in heterozygous condition. But for a recessive allele to be expressed, there has to be two copies present i.e. it has to be in homozygous recessive condition for a recessive allele to be expressed.

But in pseudodominace, only one copy of recessive allele would get expressed. That’s why we say recessive allele mimics the dominant pattern.

Examples:

Sex Chromosome:

Females have two X chromosomes (XX) but males have only one X chromosome (XY). That means females would have two alleles of every gene present on X chromosome whereas males would have only one allele. So for a female to express any recessive allele on X chromosome it has to be in homozygous condition. But in case of male whatever allele is present on their single X chromosome that would get expressed. It can be either dominant allele or recessive allele. What I mean is, for males even one recessive allele is enough on X chromosome to express it because it doesn’t have homologous X chromosome. Therefore in case of males recessive allele on X chromosome mimics the dominant pattern and thus it is an example of pseudodominance.

Autosomal Chromosome:

Pseudodominance can be seen in autosomal chromosomes when in a homologous pair of chromosome, one allele is deleted and the other allele is recessive. So here that one recessive allele will get expressed because the other allele is deleted.

Why because of pseudodominance males are more commonly and severely affected with X-linked recessive genetic disorders?

X-linked genetic disorders such as hemophilia and color blindness are recessive genetic disorders which mean they require two copies of recessive alleles in order have the disorder. So for females there has to be homozygous recessive condition for this disorder but for males only one recessive allele would result in these disorders. Therefore, males are more susceptible than females.

I hope this helps 🙂

Watch a video on this topic here.