Associations of CYP24A1 copy number variation with vitamin D deficiency and insulin secretion

Vitamin D plays an important role in insulin secretion. As the enzyme that initiates degradation of the active metabolite of vitamin D (1,25-(OH)₂ vitamin D), 24-hydroxylase encoded by CYP24A1 may be associated with insulin secretion. In this study, we aimed at investigating the association between copy number of CYP24A1 and the concentration of insulin. Included in the study were 1528 rural people from Henan Province of China. The copy number of CYP24A1 and the concentrations of serum 25(OH) vitamin D₃ and insulin were determined. Association between copy number of CYP24A1 and vitamin D deficiency was investigated with logistic regression model. Correlation between copy number of CYP24A1 and serum insulin was observed by Spearman correlation. The results suggested that copy number variation of CYP24A1 was associated with vitamin D deficiency. Higher copy number of CYP24A1 was a risk factor for vitamin D deficiency (adjusted odds ratio: 1.199; 95% confidence interval: 1.028-1.397; P = 0.021). Furthermore, copy number of CYP24A1 was positive correlated with the concentration of serum insulin (r = 0.115; P < 0.001), regardless of vitamin D status, age, and body mass index (BMI). Increased copy number of CYP24A1 is associated with not only vitamin D deficiency but also increased serum insulin. Vitamin D supplement may be beneficial to individuals with high copy number of CYP24A1. Novelty Increased copy number of CYP24A1 was a risk factor of vitamin D deficiency. Increased copy number of CYP24A1 was associated with increased serum concentration of insulin independent of age, BMI, and vitamin D status.