However, as vitamin D3 is more effective than vitamin D2 in raising 25(OH)D concentrations and experimental evidence has revealed that binding of 1,25(OH)2D3 to its cognate nuclear vitamin D receptor (VDR) represents an important molecular event, we hypothesize that measurement of 25(OH)D3 represents a more accurate estimation of in vivo vitamin D status and may thus affect cognitive function in SLE patients [13]. The gene discussed is VDR; the disease is systemic lupus erythematosus.