Question

given the following phenotypic reactions, determine the most probable genotype:

anti-d anti-c anti-e anti-c anti-e
+ 0 + + 0

r1r2
r2r2
r2r
r1r

Explanation:

Identify the present and absent Rh antigens

Using the Rh Blood Group System knowledge point

• Anti-D: \(+\) (D antigen is present)
• Anti-C: \(0\) (C antigen is absent)
• Anti-E: \(+\) (E antigen is present)
• Anti-c: \(+\) (c antigen is present)
• Anti-e: \(0\) (e antigen is absent)

The phenotype is \(D+, C-, E+, c+, e-\), which is written as \(DcE\) or \(D.c.E.c.E\) (specifically, \(D+ C- E+ c+ e-\)).

Translate phenotype to Fisher-Race and Wiener haplotypes

Using the Wiener Nomenclature knowledge point

• Since \(D\) is present, the genotype must contain at least one \(D\) allele (\(R\)).
• Since \(C\) is absent and \(c\) is present, the individual is homozygous for \(c\) (\(cc\)).
• Since \(E\) is present and \(e\) is absent, the individual is homozygous for \(E\) (\(EE\)).
• Therefore, the complete Fisher-Race phenotype is \(DcE/DcE\) (or \(cDE/cDE\)).
• In Wiener nomenclature, the haplotype \(cDE\) is designated as \(R^2\) (or \(R2\)).

Determine the most probable genotype

Using the Rh Genotype Frequencies knowledge point

• The homozygous genotype \(R^2R^2\) (\(cDE/cDE\)) perfectly matches the phenotype \(D+, C-, E+, c+, e-\).
• Let's evaluate the given options:
• \(R^1R^2\) (\(CDe/cDE\)): would be positive for \(C\) and \(e\) (incorrect).
• \(R^2R^2\) (\(cDE/cDE\)): matches perfectly (correct).
• \(R^2r\) (\(cDE/cde\)): would be positive for \(e\) (incorrect).
• \(R^1r\) (\(CDe/cde\)): would be positive for \(C\) and \(e\), negative for \(E\) (incorrect).
• Note on \(r'r'\) (\(Cde/Cde\)): This genotype lacks the \(D\) antigen (Anti-D would be \(0\)) and lacks the \(E\) antigen, making it incorrect.

Answer:

• R1R2
• R2R2 (Correct answer)
• R2r
• R1r