Topic: Examination of blood and seminal stains
Question: Enumerate types of blood group systems, used for identification and paternity testing.
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Some of the main blood group systems used for identification and paternity testing:
ABO Blood Group System
– Based on antigens A and B on RBC surface
– Types are A, B, AB, and O
– Used for paternity testing and identification
Rh Blood Group System
– Based on RhD antigen on RBCs
– Types are Rh+ or Rh-
– Second most important after ABO system
MN Blood Group System
– Antigens M and N on RBC surface
– Alleles MM, NN, and MN
– Used for paternity exclusion
Duffy Blood Group System
– Duffy a and b antigens on RBCs and other cells
– Alleles Fya, Fyb, Fy(a-b-)
– Used in paternity testing
Kidd Blood Group System
– Based on JK antigens on RBCs
– Alleles are JK*A and JK*B
– Used for identification in forensics
HLA System
– Human leukocyte antigens
– Coded by HLA gene complex
– Used for paternity testing
Diego Blood Group
– DI(a) and DI(b) antigens
– Alleles Dia and Dib
– Used as an additional marker in paternity testing
The various blood group systems can be used for parentage testing and confirming biological relationships in the following ways:
– ABO blood groups – The alleles for A, B, and O are inherited in a Mendelian fashion from biological parents. Children may have a blood type that matches one or both parents or is a blend of the two.
– Rh blood groups – Rh factor is also inherited. Checking Rh status of alleged parents against child can help include or exclude parentage.
– MN blood groups – The M, N and MN alleles are co-dominant so checking the MN phenotype of child against potential parents can help determine biological relationships.
– Duffy system – The Fya, Fyb and Fy(a-b-) alleles are inherited in a Mendelian pattern. Checking inheritance with alleged parents can provide evidence for or against paternity.
– Kidd system – The JK*A and JK*B alleles are inherited in a codominant fashion from parents. Comparing child and alleged parents can indicate biological relationships.
– HLA typing – HLA alleles are highly polymorphic and comparing inheritance patterns between child and potential parents is very useful for confirming or excluding paternity.
– Diego blood group – The Dia and Dib alleles provide additional markers that follow Mendelian inheritance to aid paternity testing as supplemental evidence.
Overall, by testing the child and alleged parents for these blood group phenotypes and comparing the pattern of inheritance, one can mathematically calculate probability of parentage and use blood types as evidence to establish biological relationships in paternity testing.
