What is the name of a gene whose effect comes from the dominant and recessive alleles
Allelic effects


  What is the name of a gene whose effect [..]


The concept of dominance make sense for alleles. The gene has no name to refer to the allelic interaction.

Patterns of dominance

Patterns of dominance and recessivity are typically used for quantitative traits. Can you somehow put a a number into the phenotypes of all three genotypes? Making some kind of association table would help even if the phenotypes are not quantitative. See below. 

Attempt to answer the question

It looks like you are considering a case where the phenotypes

aa -&gt; healthy
Aa -&gt; sick
AA -&gt; very sick


Under this model, it is hard to tell whether you would consider sick half way through healthy and very sick or not. It feels like you want to consider sick as being closer to very sick than to healthy so if we put numbers we could get something like

aa -&gt; 1 (healthy)
Aa -&gt; 2 (sick)
AA -&gt; 2.5 (very sick)


As such, A shows partial dominance (aka incomplete dominance or semi-dominance).