Are there some methods can be used to do association analysis in a very small size group?

Sorry that I’m not native English speaker, so maybe I did not make myself clear somewhere. If so, please forgive me and welcome to ask.

we foung a new trait in our animal group so we wanted to detect potential associated variants. However, we only have very small size sample group because the trait is novel. We have 2 cases and 3 controls:1 father, 2 monthers and 2 offsprings. All is WGS data.

So are there some methods can be used to do association analysis in such a small size group? Better with using family pedigree information as well. We cannot find a effective way to do analysis within our experience, obviously usual GWAS can not get a significant result. We tried gene-level association study but also got no sigificant result.