Supplementary Material for: Effects of Gene Variants Controlling Vitamin D Metabolism and Serum Levels on Hepatic Steatosis

<b><i>Background/Aims:</i></b> Common genetic variations in vitamin D metabolism are associated with liver stiffness. Whether these genes are implicated in hepatic steatosis remains unclear. Here we aimed to analyse the association of common vitamin D pathway gene variants with liver steatosis. <b><i>Methods:</i></b> Liver steatosis was assessed non-invasively in 241 patients with chronic liver conditions by controlled attenuation parameter (CAP). The following polymorphisms were genotyped using TaqMan assays: group-specific component (<i>GC</i>) rs7041, 7-dehydrocholesterol reductase (<i>DHCR7</i>) rs12785878, cytochrome P450 2R1 (<i>CYP2R1</i>) rs10741657, ­vitamin D receptor (<i>VDR</i>) rs7974353. Chemiluminescence immunoassay determined serum 25-hydroxyvitamin D (25(OH) D) concentrations. <b><i>Results:</i></b> Vitamin D deficiency (defined by 25(OH)D concentrations <20 ng/mL) occurred in 66% of patients. Median CAP was 296 (100–400) dB/m. Patients with advanced steatosis (CAP ≥280 dB/m) had significantly (<i>p</i> = 0.033) lower 25(OH)D levels as compared to patients with CAP <280 dB/m. Moreover, the rare allele [T] in <i>GC</i> rs7041 was significantly (<i>p</i> = 0.018) associated with higher 25(OH)D levels in patients with CAP <280 dB/m. However, <i>GC</i>, <i>DHCR7,</i> <i>CYP2R1</i>, and <i>VDR</i> polymorphisms were not related to liver steatosis and obesity traits. <b><i>Conclusions:</i></b> Higher CAP values are associated with low serum 25(OH)D concentrations but not with common vitamin D pathway gene variants.