The Saccharomyces cerevisiae pol3-D321N mutation mimicking human POLD1-D316N elevates the mutation rate in haploid strains when no wild-type POL3 allele is present.
References:
Murphy, K., Darmawan, H., Schultz, A., da Silva, E.F. & Reha-Krantz, L.J. A method to select for mutator DNA polymerase δs in Saccharomyces cerevisiae. Genome 49, 403–410 (2006). https://pubmed.ncbi.nlm.nih.gov/16699561/