GSTM1 and chronic kidney disease: We searched PubMed/Medline, Cochrane Library, and Google Scholar from inception to 21st April 2023, using the search string: (vitamin D supplementation OR Calciferol OR cholecalciferol OR 1,25-Dihydroxycholecalciferol) AND (Anemia OR low Hb OR hemoglobin) AND (CKD OR chronic kidney disease OR chronic kidney failure OR dialysis OR hemodialysis).