In the "GWASTools" R Package, the "assocRegression" function allows GWAS with interactions. Suppose my model is:

y ~ a + b*z + c*G + d*(z * G)

where y=RESPONSE, z=Interacting variable, and G=Genomic factor.

The "assocRegression" returns tests on the following null hypotheses {c=0} , {d=0}, and {c=0, d=0} .

Is it possible for it to also test {b=0,d=0}? This is the joint hypothesis where the interacting variable "z" has no effect (with no restriction on the non-interacting genomic effect).

Thank you.