Of the 115 statistically significant mito-nuclear interactions found in the TCGA data set, one nuSNP in an intron of WSC Domain Containing 2 (WSCD2) was found to interact with a mtSNP in the mitochondrially-encoded NADH dehydrogenase 4 (MT-ND4) gene leading to a significant increase of as much as ~ 12% in the mean size of nuclei and was confirmed in the METABRIC breast cancer tissue cohort as an independent data set. The gene discussed is MT-ND4; the disease is breast cancer.