メチレンテトラヒドロ葉酸還元酵素遺伝子多型とゲノムDNAハイメチル化レベルの強直性脊椎炎との相関

[Correlations of Methylenetetrahydrofolate Reductase Gene Polymorphism and Genomic DNA Hypomethylation Level with Ankylosing Spondylitis].

• Ni Mao
• Jinwei Chen
• Jia Wang
• Xi Xie
• Fen Li
• Yiming Liu

抄録

DNAメチル化レベルおよびメチレンテトラヒドロ葉酸還元酵素(MTHFR)遺伝子多型と強直性脊椎炎(AS)との関係を検討した。 中国湖南省のHLA-B27(+)のAS患者200名と健常者120名を対象に，1984年のニューヨーク基準に基づいて診断を行った．DNAメチル化はシトシン伸長法で、MTHFR遺伝子C677T多型はポリメラーゼ連鎖反応（PCR）と制限断片長多型（RFLP）で解析した。 その結果、AS群のT/T遺伝子型変異の割合は対照群に比べて有意に高く(17.0% 5.0%;=9.874,=0.002)、AS群の血漿中ホモシステイン濃度は(18.71±2.42)&#x3BC;mol.42であった。また、T/T遺伝子型の血漿中ホモシステイン濃度は18.71±2.42μmol/Lであり、正常対照群[10.97±2.93μmol/L](=24.402,<0.001)に比べて有意に高かった。μmol/L]は、C/C遺伝子型[(18.31±1.94)μmol/L](=12.088, =0.01)及びC/T遺伝子型[(17.80±2.18)μmol/L](=6.496, =0.01)と比較して、AS群の血漿中Hcy濃度が有意に高かった。AS群のT/T遺伝子型のDNAメチル化レベルは、正常対照群(=5.655、<0.001)に比べて有意に低く、また、AS群のC/C遺伝子型(=11.514、<0.001)とC/T遺伝子型(=10.287、<0.001)に比べても有意に低かった。 MTHFR遺伝子の677位のT/T変異はゲノムDNAのメチル化低下と関連しており、DNAのメチル化低下はASの発症機序の一つである可能性が示唆された。

To investigate the relationship of both DNA methylation level and methylenetrahydrofolate reductase(MTHFR)gene polymorphism with ankylosing spondylitis(AS). Totally 200 Chinese AS patients with HLA-B27(+)and 120 healthy controls were included from Hunan Province.All the cases were diagnosed according to the 1984 modified New York criteria for AS.The DNA methylation was examined by cytosine extension method,while the MTHFR gene C677T polymorphism was analyzed by the polymerase chain reaction(PCR)and restriction fragment length polymorphism(RFLP).The plasma homocysteine(Hcy)level was examined by enzyme-linked immunosorbent assay(ELISA),while the red blood folate level was analyzed by the specific immunoassays. The ratio of the T/T genotype mutation in the AS group was significantly higher than in the control group(17.0% 5.0%;=9.874, =0.002).The plasma homocysteine concentration of AS group was(18.71 ± 2.42)μmol/L,which was significantly higher than that in normal control group [(10.97 ± 2.93)μmol/L](=24.402, <0.001).The plasma Hcy concentration of the T/T genotype [(21.70±1.80)μmol/L] was significantly higher than that of the C/C genotype[(18.31±1.94)μmol/L](=12.088, =0.01)and the C/T genotype [(17.80±2.18)μmol/L](=6.496, =0.01)in the AS group.The DNA methylation level of the T/T genotype in AS group was significantly lower than that in normal control group(=5.655, <0.001)and also significantly lower than those of the C/C genotype(=11.514, <0.001)and the C/T genotype in AS group(=10.287, <0.001). In the Han population in Hunan Province,the C677T polymorphism of the MTHFR gene is associated with the onset of AS.The T/T mutation at position 677 of the MTHFR gene is an important influencing factor for hyperhcyemia in the AS patients.The T/T mutation at position 677 of the MTHFR gene is associated with genomic DNA hypomethylation.Thus,hypomethylation of DNA may be one of the pathogenic mechanisms of AS.