Analysis of the pairwise variation in DLB and control grouping demonstrated a V2/3 = 0.135; therefore although the inclusion of a fourth gene was found to improve the pairwise variation (Additional File 7C), the use of three reference genes (UBC, GAPDH, B2M) for normalisation of data in this group would be adequate. The gene discussed is UBC; the disease is Lewy body dementia.