| 摘要: | 前言:許多研究已證實鉛、鎘、汞與砷等化學物質具有神經毒性，影響腦部生理活動，導致認知功能低下、感覺與語言障礙與發展遲緩等現象。遺傳因素可能也會影響砷代謝能力，進而影響疾病發生。因此本研究目的為瞭解血液重金屬濃度、砷代謝能力、單碳代謝相關酵素基因型與兒童發展遲緩之相關性。
材料與方法:研究對象為新光醫院復健科經醫師判定為發展遲緩兒童與小兒科門診的正常發展兒童。經受過訓練之訪員向研究對象說明研究目的，且研究對象母親簽署同意書後進行問卷訪視，並收集尿液與血液等生物檢體。尿液利用高效能液相層析儀串聯氫化器與原子吸收光譜儀分析尿液砷物種濃度。血液經分離後，以淋巴球層萃取 DNA 並利用聚合酶連鎖反應增幅 DNA片段，及限制片段長度多形性方法分析研究對象之單碳代謝相關酵素基因型。血球經微波消化後，利用感應耦合電漿質譜儀測定鉛、鎘與汞的濃度。
結果:本研究發現發展遲緩兒童之血鉛濃度、無機砷酸百分比與單甲基砷酸百分比均顯著高於正常發展兒童，而雙甲基砷酸百分比顯著低於正常發展兒童。隨著血鉛濃度、無機砷酸百分比與單甲基砷酸百分比上升，兒童發展遲緩危險對比值顯著增加。在調整多變項後，MTHFR C677T 攜帶CT與TT基因型者相較於CC基因型者，兒童發展遲緩危險對比值顯著降低，其危險對比值與95%信賴區間為0.25 (0.10-0.64)。砷代謝能力與MTHFR C677T基因型對兒童發展遲緩評估聯合效應發現隨著砷代謝能力較差且攜帶MTHFR C677T CC基因型，兒童發展遲緩危險對比值隨顯著增加。攜帶MTHFRA[1298]C-C[677]T風險雙倍體A-C/A-C, A-C/C-C, C-C/C-C相對於非風險雙倍體A-C/A-T, A-T/C-C, A-T/A-T者，在調整多變項後，兒童發展遲緩危險對比值與95%信賴區間為3.93 (2.03-7.60)。MTHFRA[1298]C-C[677]T風險雙倍體A-C/A-C, A-C/C-C, C-C/C-C及無機砷酸百分比對兒童發展遲緩危險對比值有顯著的加成性之交互作用存在，synergy index與95%信賴區間為4.72 (1.13-19.61)。在未調整任何干擾因子下，母親尿液總砷濃度與兒童尿液總砷濃度有顯著相關(R² = 0.0521, p = 0.0027)、母親的無機砷酸百分比與兒童的無機砷酸百分比之亦呈顯著相關(R² = 0.0372, p = 0.0115)。調整所有可能影響兒童尿液總砷濃度之因子後，仍發現兒童尿液總砷與母親尿液總砷濃度呈顯著相關。
結論:隨著兒童血鎘與血鉛濃度上升及兒童砷代謝能力愈差，兒童發展遲緩的危險對比值顯著上升，並呈劑量效應關係。MTHFR C677T帶有CC基因型者相較於CT與TT基因型者有顯著較高的兒童發展遲緩危險對比值。母親尿液總砷濃度與兒童尿液總砷濃度呈顯著正相關。攜帶MTHFR C677T CC基因型且砷代謝能力愈差者，兒童發展遲緩危險性較高， 基因型與砷之間並未存在交互作用關係。攜帶MTHFR A[1298]C-C[677]T/A[1298]C-C[677]T之風險雙倍體A-C/A-C, A-C/C-C, C-C/C-C且砷代謝能力愈差者，兒童發展遲緩危險性較高。
Background:Many studies have confirmed that various neurotoxic chemical such as lead, cadmium, mercury, and arsenic may affect brain physiological activities, causing cognitve dysfunction, sensory, language disorder and developmental disabilities. Genetics may also affect the capacity of arsenic metabolism, thereby causing diseases to occur. Therefore, this study looks at the relationship between the level of blood metals, arsenic metabolism capacity, the polymorphism of one-carbon metabolism-related enzymes and the developmental delays in children.
Methods
We recruited children who were diagnosed with developmental delays by physicians from the Department of Rehabilitation and healthy children recruited from the Department of Pediatric of Shin Kong hospital. Well-trained assistants performed the standardized personal interview using a structured questionaire for the study subjects and collected their biospecimens after obtaining informed consent. Urinary arsenic concentration was detected using a high-performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. The genotype of MTHFR and MTR were determined using DNA fragments, which were extracted and amplified by Polymerase Chain Reaction, and restriction fragment length polymorphism method. After blood digestion, the concentration of lead, cadmium and mercury were measured by inductively coupled plasma mass spectrometry.
Results:The study found that the children with developmental delays had significantly higher levels of lead in blood, InAs% and MMA% , but significantly lower DMA% than children with normal development. Additionally, higher levels of lead in blood, InAs% and MMA%, showed an increased risk of developmental delays in children. After multivariable adjustment, children with the MTHFR CT and TT genotypes were compared to children with the MTHFR CC genotype, and results showed that children with the MTHFR CT and TT genotypes demonstrated significantly decreased risk of children’s developmental delays with an odds ratio and 95% CI=0.25(0.10-0.64). When assessing the combined effects of arsenic methylation capacity and the MTHFR C677T genotype on children’s developmental delay, we found that children with both poor arsenic metabolism capacity and the MTHFR C677T CC genotype had significantly increased risk of developmental delay. After adjustment, children with the MTHFR A[1298]C-C[677]T risk haplotype A-C/A-C, A-C/C-C, C-C/C-C were compared with children the MTHFR A[1298]C-C[677]T without risk haplotype A-C/A-T, A-T/C-C, A-T/A-T, and the odds ratio and 95% confidence interval of children’s developmental delay among those carrying the MTHFR A[1298]C-C[677]T risk haplotype A-C/A-C, A-C/C-C, C-C/C-C was 3.93(2.03-7.60). There was additive interaction on children’s developmental delay between the MTHFR A[1298]C-C[677]T risk haplotype A-C/A-C, A-C/C-C, C-C/C-Cand InAs%, and the synergy index and 95% CI were 4.72(1.13-19.61). Before adjusting any confounding factors, we found significant correlation between mother and child’s total urinay arsenic level and also significant correlation between mother and child’s MMA%. After adjusting for confounding factors which may have affected the level of total urinay arsenic, we still found significant correlation between mother and child’s total urinay arsenic level.
Conclusions:The study found that children with increased levels of blood cadmium and lead had significantly decreased arsenic methylation capacities as well as significantly increased risk of developmental delays. Children with the MTHFR CC genotypes were compared to chidren with the MTHFR CT and TT genotypes had significantly increased risk of developmental delay. The correlation of total urinay arsenic levels between mother and children was significant. Children with both MTHFR C677T CC genotype and poor arsenic methylation capacity had significantly increased risk of developmental delays. Carriers of the MTHFR A[1298]C-C[677]T risk haplotype A-C/A-C, A-C/C-C, C-C/C-C and poor arsenic metabolism capacity had significantly increased risk of developmental delays. |
