02298nas a2200241   4500000000100000008004100001100001200042700001300054700001700067700001600084700001800100700001900118700002500137700001900162700002000181700002300201700002700224700001100251700001600262245010400278520166000382022001402042       2017                            d1 aDwyer T1 aSun Cong1 aPezic Angela1 aKemp Andrew1 aEllis Justine1 aCameron Fergus1 aPonsonby Anne-Louise1 aBima Abdulhadi1 aRodda Christine1 avan der Mei Ingrid1 aChiaroni-Clarke Rachel1 aQu Jun1 aCarlin John00aEnvironmental and genetic determinants of two vitamin D metabolites in healthy Australian children.3 a<p>
<b>BACKGROUND: </b>Vitamin D deficiency has been associated with adverse health outcomes. We examined genetic and environmental determinants of serum 25(OH)D3 and 1,25(OH)2D3 in childhood.
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<b>METHODS: </b>The study sample consisted of 322 healthy Australian children (predominantly Caucasians) who provided a venous blood sample. A parental interview was conducted and skin phototype and anthropometry measures were assessed. Concentrations of 25(OH)D3 and 1,25(OH)2D3 were measured by selective solid-phase extraction-capillary liquid chromatography-tandem mass spectrometry. These concentrations were deseasonalised where relevant to remove the effect of month of sampling.
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<b>RESULTS: </b>Deseasonalised log 25(OH)D3 and 1,25(OH)2D3 concentrations were only moderately correlated (r=0.42, p&lt;0.001). The following predicted both 25(OH)D3 and 1,25(OH)2D3: UVR 6 weeks before the interview, natural skin and eye colour, height and vitamin D allelic metabolism score. The following predicted 25(OH)D3 only: lifetime sunburns and vitamin D allelic synthesis score. Overall, 43.5% and 25.6% of variation in 25(OH)D3 and 1,25(OH)2D3 could be explained. After accounting for 25(OH)D3 concentrations, higher UVR 6 weeks before the interview and vitamin D allelic metabolism score further predicted 1,25(OH)2D3 concentrations.
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<b>CONCLUSIONS: </b>Environmental factors and genetic factors contributed to both vitamin D metabolite concentrations. The intriguing finding that the higher ambient UVR contributed to higher 1,25(OH)2D3 after accounting for 25(OH)D3 concentrations requires further evaluation.
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