Blood groups and stains

🖇 Human Genetically Controlled Marker Systems

Determine individual differences through:

📌 Blood group systems (ABO, Rh).

📌 Enzyme groups

Polymorphic enzymes located in RBCs.

📌 Protein groups

Haptoglobins, immunoglobulin types in plasma.

📌 HLA (Human Leukocyte Antigen)

Present on WBCs.

Highly complex → chance of two unrelated individuals having identical HLA type is extremely low.

🟠 Disputed Paternity – Key Situations

Babies claimed by two different sets of parents.

Accidental switching of babies in maternity units.

Father denying paternity.

Lost child recovered after long interval → identity must be confirmed.

🟣 Physician Responsibilities to Avoid Blood Incompatibility

📌 Accurate blood grouping (ABO + Rh) for donor and recipient before each transfusion.

📌 Direct cross-matching: donor blood + recipient blood → no agglutination.

📌 Avoid using Group O as a universal donor

Some O donors have potent agglutinins that can hemolyze A or B RBCs.

📌 Transfused blood must be Rh-negative, especially for female recipients.

📌 Avoid transfusing husband’s blood to his wife

Prevents future fetal complications.

📌 Donor must be free from infectious diseases

e.g., hepatitis viruses, HIV.