Covariates considered were: age, sex, Iso-Resources Groups (GIR) score ≤ 3, Parathyroid hormone (PTH), C-Reactive Protein (CRP), severe undernutrition defined as albumin < 30 g/L, history of cancer, history of cardiomyopathy, severe chronic renal failure (defined as clearance < 30 ml/min), Ordinal Scale for Clinical Improvement (OSCI) score, use of systemic corticosteroids and usual vitamin D supplementation. The gene discussed is CRP; the disease is chronic kidney disease.