Which Lewis genotype results in the phenotype Le(a-b-)?

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Multiple Choice

Which Lewis genotype results in the phenotype Le(a-b-)?

Le(a-b-) on red cells means neither Lea nor Leb is present. The Lewis antigens are produced by the FUT3 enzyme (the Lewis gene). If FUT3 is nonfunctional (le), neither Lea nor Leb can be synthesized, so the red cells lack Lewis antigens regardless of secretor status or H antigen. That makes Le(a-b-) the outcome when the genotype is lele, even when H is present (HH) and the person is a secretor or not. In this case, lele with HH SeSe guarantees there’s no Lewis antigen production, yielding Le(a-b-). The other genotypes would allow some Lewis antigen expression if FUT3 were functional, depending on secretor status, so they do not produce Le(a-b-).

Le(a-b-) on red cells means neither Lea nor Leb is present. The Lewis antigens are produced by the FUT3 enzyme (the Lewis gene). If FUT3 is nonfunctional (le), neither Lea nor Leb can be synthesized, so the red cells lack Lewis antigens regardless of secretor status or H antigen. That makes Le(a-b-) the outcome when the genotype is lele, even when H is present (HH) and the person is a secretor or not. In this case, lele with HH SeSe guarantees there’s no Lewis antigen production, yielding Le(a-b-). The other genotypes would allow some Lewis antigen expression if FUT3 were functional, depending on secretor status, so they do not produce Le(a-b-).

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