Seremak-Mrozikiewicz Agnieszka
Klinika Perinatologii i Chorób Kobiecych, Uniwersytet Medyczny w Poznaniu, Polska.
Ginekol Pol. 2013 May;84(5):377-84. doi: 10.17772/gp/1593.
Proper metabolism of folates has a crucial role for body homeostasis. Folate metabolism regulates changing of amino acids (homocysteine and methionine), purine and pyrimidine synthesis and DNA methylation. These whole biochemical processes have significant influence on hematopoietic, cardiovascular and nervous system functions. The disturbances of folate cycle could result in chronic hypertension, coronary artery disease, higher risk of heart infarction, could promote cancers development, and psychic and neurodegenerative diseases. No less important is the connection with complications appearing in pregnant woman (recurrent miscarriages, preeclampsia, fetus hypotrophy intrauterine death, preterm placenta ablation, preterm delivery) and fetus defects (Down syndrome, spina bifida, encephalomeningocele, myelomeningocele). The complex process of folate metabolism requires adequate activity of many enzymes and presence of co-enzymes. A key enzyme in folate metabolism is methylenetetrahydrofolate reductase (MTHFR - methylenetetrahydrofolate reductase), and 677C>T polymorphism of MTHFR gene is connected with lower enzymatic activity In several researches it was indicated that 677C>T MTHFR polymorphism is an independent factor influencing homocysteine concentration in serum, and also folate concentration in serum and red blood cells. Nevertheless, it was also observed the correlation of 677C>T MTHFR polymorphism with Down syndrome, and neural tube defects appearance in fetus. In European populations frequency of mutated 677TT genotype ranges from a few to several percent. Women carriers of 677TT or 677CT MTHFR genotypes are exposed on folate metabolism disturbances and on the consequences of incorrect folate process during pregnancy Nowadays in this group of women folic acid supplementation is widely recommended. In the light of modern knowledge the attention was also focused on the importance of metafolin administration that omitted pathways of folic acid transformation after administration, and in pregnant women certainly is valuable complement of supplementation in this respect.
叶酸的正常代谢对身体内环境稳定起着关键作用。叶酸代谢调节氨基酸（同型半胱氨酸和甲硫氨酸）的变化、嘌呤和嘧啶的合成以及DNA甲基化。这些整个生化过程对造血、心血管和神经系统功能有重大影响。叶酸循环紊乱可能导致慢性高血压、冠状动脉疾病、心肌梗死风险增加，促进癌症发展以及引发精神和神经退行性疾病。同样重要的是与孕妇出现的并发症（反复流产、先兆子痫、胎儿宫内发育迟缓、宫内死亡、早产胎盘早剥、早产）以及胎儿缺陷（唐氏综合征、脊柱裂、脑膨出、脊髓脊膜膨出）的关联。叶酸代谢的复杂过程需要多种酶的充分活性和辅酶的存在。叶酸代谢中的关键酶是亚甲基四氢叶酸还原酶（MTHFR - 亚甲基四氢叶酸还原酶），MTHFR基因的677C>T多态性与较低的酶活性相关。在多项研究中表明，677C>T MTHFR多态性是影响血清同型半胱氨酸浓度以及血清和红细胞中叶酸浓度的独立因素。然而，也观察到677C>T MTHFR多态性与唐氏综合征以及胎儿神经管缺陷出现的相关性。在欧洲人群中，突变的677TT基因型频率从百分之几到百分之几十不等。677TT或677CT MTHFR基因型的女性携带者在孕期会面临叶酸代谢紊乱以及叶酸代谢不正确的后果。如今，在这组女性中广泛推荐补充叶酸。根据现代知识，注意力也集中在活性叶酸制剂给药的重要性上，其省略了给药后叶酸转化的途径，在孕妇中这肯定是这方面补充的有价值的补充。
