In ABO saliva testing, when is the f antigen expressed?

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Multiple Choice

In ABO saliva testing, when is the f antigen expressed?

In ABO saliva testing, the appearance of the fucose-containing antigen in saliva depends on how the related gene variants are arranged on the same chromosome. The f antigen is expressed only when the f allele and the ce haplotype are in cis—that is, on the same chromosome. This coupling allows the secretor-type fucosyltransferase activity to act in secretory tissues and produce the f antigen in saliva. If ce and f are on opposite haplotypes, the necessary combination isn’t present in the same chromosome, so the f antigen isn’t expressed. The other options don’t fit because they either ignore the need for this cis arrangement or incorrectly tie the f antigen expression to the D antigen.

In ABO saliva testing, the appearance of the fucose-containing antigen in saliva depends on how the related gene variants are arranged on the same chromosome. The f antigen is expressed only when the f allele and the ce haplotype are in cis—that is, on the same chromosome. This coupling allows the secretor-type fucosyltransferase activity to act in secretory tissues and produce the f antigen in saliva. If ce and f are on opposite haplotypes, the necessary combination isn’t present in the same chromosome, so the f antigen isn’t expressed. The other options don’t fit because they either ignore the need for this cis arrangement or incorrectly tie the f antigen expression to the D antigen.

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