Analysis For The Effect Of Genetic Variants In Vitamin D Metabolism Pathway On Vitamin D Level And Bone Mass Development In Children And Adolescents

ObjectivesThis study aimed to understand the status of vitamin D nutritional level and bone mass development in children and adolescents aged 6-17;to analyze the influencing factors of vitamin D deficiency and insufficient bone mass development in children and adolescents aged 6-17;and to evaluate the effect of genetic variants?DHCR7,GC,CYP2R1,CYP24A1?in vitamin D metabolism pathway on vitamin D deficiency and insuffic-ient bone mass development in children and adolescents.MethodsBased on the baseline survey of the body composition and health promotion project for primary and middle school students in Guangzhou,the convenience sampling method was used to selected 2023 children and adolescents aged 6-17 for the survey in April and May 2019.We collect information on diet,vitamin D supplement intake,sunscreen products,and exercise of students through questionnaires.Whole body bone mineral density of students was measured with the dual energy X-ray absorptio-metry.Age and gender standardized calculations were performed on total body less head bone mineral density to obtain Z score for the bone mass development evaluation?Z score?0 indicates normal bone mass,-1?Z score<0 means insufficient bone mass development,Z score<-1 for severe insufficient bone mass development?.We selected the common potential functional genetic variants of vitamin D metabolism-related genes through screening for publications of genome-wide association studies and bioinformatics analysis methods?DHCR7 rs12785878,rs1790349;GC rs4588,rs7041,rs1155563;CYP2R1 rs10741657,rs12794714;CYP24A1 rs6013897,rs2209314?.Genotyping was detected by TaqMan real-time quantitative PCR and serum 25?OH?D level was detected by electrochemical luminescence?25?OH?D>75 nmol/l indicates vitamin D sufficiency,50?25?OH?D?75nmol/l means vitamin D insu-fficiency,and 25?OH?D<50nmol/l for vitamin D deficiency?.Chi-square test was used to compare vitamin D deficiency in subjects with different characteristics.The T-test and analysis of variance were used to compare vitamin D level among different characteristics populations.The effect of genetic variants and genetic risk score?GRS?on vitamin D level were estimated by generalized linear regression model.The log-binomial model was applied to analyze the influencing factors of lifestyle on insufficient bone mass development,and to evaluate the effects of genetic variants and GRS on vitamin D deficiency and insufficient bone mass development.Results1.A total of 1971 children and adolescents aged 6-17 were finally included in this study.The average serum vitamin D level of subjects was64.97±20.36 nmol/l.The vitamin D level was highest among children aged 6-9 and lowest among adolescents aged 10-13?F=33.22,P<0.001?.Boys have higher vitamin D level than girls?t=6.77,P<0.001?.The vitamin D deficiency rate of subjects was 22.68%?447/1971?.The vitamin D deficiency rate was highest among adolescents aged 10-13 and lowest among children aged 6-9??²=29.84,P<0.001?.The vitamin D deficiency rate was lower in boys than that in girls??²=20.69,P<0.001?.Students with aquatic product intake frequency?3times/week or weekend outdoor activity time?2h/d have higher vitamin D level.The student who regularly used sunscreen products have lower vitamin D level?P<0.05?.2.In genetic association analysis for vitamin D level,compared with DHCR7 rs12785878 GG genotype,the vitamin D level of GT and TT genotype were increased by 3.791 nmol/l and 4.757 nmol/l,respec-tively(P_FDR<0.05).Under the recessive model,the vitamin D level of rs1790349 CC genotype was reduced by 4.520 nmol/l compared with TT+TC genotype(P_FDR=0.041).The vitamin D level of GC rs7041 AC and CC genotype were increased by 3.454 nmol/l and 6.241 nmol/l,respectively,compared with AA genotype(P_FDR<0.05).Compared with GC rs4588 GG genotype,the vitamin D level of GT and TT genotype were reduced by 6.346 nmol/l and 14.894 nmol/l(P_FDR<0.05).The level of vitamin D in student who carry with GC rs1155563 TC and CC genotype were lower compared with TT genotype(?=-3.214;?=-7.849,P_FDR<0.05).CYP2R1 rs12794714 AA genotype carriers have lower vitamin D level than GG genotype carriers(?=-7.229,P_FDR<0.05).3.In genetic association analysis for vitamin D deficiency,the T allele of DHCR7 rs12785878 and C allele of GC rs7041 can reduce the risk of vitamin D deficiency in students(P_FDR<0.05).The T allele of GC rs4588 and C allele of rs1155563 increased the risk of vitamin D deficiency in students(P_FDR<0.05).Moreover,we found that DHCR7rs1790349 CC genotype carriers have an PR of 1.55?95%CI=1.10?2.10?compared with TT genotype.Under the dominant model,CYP24A1rs6013897 allele mutation has a statistically tendency to increase the risk of vitamin D deficiency(P_FDR=0.050).4.In the genetic risk score analysis,compared with the GRS risk level Q1,the serum vitamin D of Q3 was reduced by 5.939 nmol/l?P=0.002?,and the PR for vitamin D deficiency was of 1.82?95%CI=1.12?2.99?.The serum vitamin D of Q4 decreased by 10.264 nmol/l(P=1.598×10^-10),and the vitamin D deficiency PR value was of 2.30?95%CI=1.52?3.53?.5.Bone mineral density of children and adolescents increased with age.We found that the age curve of bone mineral density in boys and girls have"two crossings"around the age of 10 and 13.The rate of insufficient bone mass development in children and adolescents is39.96%?786/1971?.In the multivariate analysis,the intake frequency of milk and dairy products?3 times/week?PR=0.85,95%CI=0.77?0.95?,and extracurricular exercise?PR=0.84,95%CI=0.76?0.94?were associat-ed with the increased bone mass in children and adolescents.Based on the stratification analysis by age,vitamin D deficiency among students aged 10-13 years and 14-17 years could increase the risk of insufficient bone mass development by 36%?PR=1.36,95%CI=1.04?1.80?and 52%?PR=1.52,95%CI=1.09?2.16?,respectively.6.In genetic association analysis for bone mass development,we found under the dominant and additive genetic model of multi-factor analysis,the allele mutation of GC rs7041 can increase the risk of insufficient bone mass development?dominant model:PR=1.11,95%CI=1.00?1.23;additive model:PR=1.08,95%CI=1.00?1.17?,but no statis-tical significance after FDR correction.In addition,under the recessive model of univariate analysis,the risk of insufficient bone mass development in CYP2R1 rs10741657 AA genotype was lower than the GG+GA genotype?PR=0.81,95%CI=0.66?0.98?,but no statistical significance after FDR correction.We used GRS to analyze the cumula-tive effect of gene variants on bone mass development,but found no statistical correlation.Conclusions1.Vitamin D deficiency is prevalent among children and adolescents.The vitamin D deficiency rate is increase with age.The vitamin D deficiency rate is higher among people who eat less aquatic products and have shorter outdoor activities.In addition,vitamin D deficiency rate is higher in girls and people who regularly use sunscreen products.2.The variants,including the DHCR7 rs12785878,rs1790349,GC rs4588,rs7041,rs1155563,CYP2R1 rs12794714,and CYP24A1rs6013897,are associated with serum vitamin D level and the risk of vitamin D deficiency.And these variants have a cumulative effect on vitamin D deficiency.3.The bone mineral density of children and adolescents increases with age,and the bone mineral density of boys and girls have the phenomenon of"two crossings"around the age of 10 and 13.Intake of milk and dairy products,extracurricular exercises and sufficient vitamin D level can promote bone mass development in children and adolescents.4.No association was found between the genetic variants in DHCR7,GC,CYP2R1,CYP24A1 and bone mass development in children and adolescents.