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Si̇nan beksaç
- 1. Vanishing Twins & MTHFR Gene Polimorphisms; Coincidence or Biological Fact Prof. M. Sinan Beksaç, Head of Perinatal Medicine, Department of Obstetrics and Gynecology Hacettepe University, Ankara
- 2. Vanished fetus in multiple pregnancy • Vanishing Twin: One fetus with positive FHR plus gestational sac/fetus without FHR at 8th gestational week • One growing fetus plus one small gestational sac/fetus without FHR at 12-14 gestational week. • Single fetus at 20th gestational week
- 3. 35 vanishing twins between «January 2010- December 2012» & Methylene Tetra Hydrate Folate Reductase Gene Polimorphisms • MTHFR 1317 polimorphism is not included • Other mutations ! MTHFR Enzyme Mutations Number % Normal 4 10,5 Heterozygot A1298C 9 23,7 Heterozygot C677T 2 5,3 Heterozygot 677+1298 (compound Heterozygot ) 9 23,7 Homozygot A1298C 5 13,2 Homozygot C677T 6 15,8 Total 35 100
- 4. The rate of MTHFR polimorphisms in «vanishing twin» cases is more than 90 %. If this is true what is the biological fact behind «vanishing twins» • «Methylene Tetra Hydro Folate Reductase» which is mainly responsible from the METHYLATION processes of other substances (enzymes, aminoacids, nucleotids, DNA, etc) & ENZYME ACTIVITY IS REDUCED… MTHFR Mutations Enzyme Activity Homozygote C677T mutation 66% Heterozygote C677T mutation 33% Homozygote A1298C mutation 40% Heterozygote A1298C mutation 40% Compound Heterozygotes C677T & A1298C ?? 1317 mutations ??
- 5. Is «vanishing twin» the result of …. • Impaired methylation processes? • Or can we talk about «complex enzyme pathway disorders»
- 6. We do not know the answer ? • Multifactorial ! • Genetical! • Impaired gametogenesis • Hereditary factors • Embryogenesis problem • Environmental/ teratological factor (ICSI/IVF; about 10 %) • Metabolic • Male factor
- 7. We do not know the biological fact behind vanishing twins! But we are free to think about it !!!
- 9. MethionineHomocysteine Methionine Synthase B12 Methyltetrahydrofolate (active folic acid) Tetrahydrofolate Methylenetetrahydrofolate (dietary folic acid) MTHFR dUMP dTMP DNA-Thymine Cysteine and Propionyl-CoA B6 Cystathionine b-Synthase SAM (S-Adenosyl-L-methionine) SAH (S-Adenosyl-L-homocysteine) ATP MethionineHomocysteineHomocysteineHomocysteineHomocysteine Dihydrofolate B2, B3, B6! monohydrofolate dihydrofolate B2, B3, B6! Impaired Methylation Cytosine 5-Methylcytosine Methyl Group DNA Methyltransferase Gene Switched “on” TRANSCRIPTION Gene Switched “off” NO TRANSCRIPTION
- 11. MethionineHomocysteine Methionine Synthase B12 Methyltetrahydrofolate (active folic acid) Tetrahydrofolate Methylenetetrahydrofolate (dietary folic acid) MTHFR dUMP dTMP DNA-Thymine Cysteine and Propionyl-CoA B6 Cystathionine b-Synthase SAM (S-Adenosyl-L-methionine) SAH (S-Adenosyl-L-homocysteine) ATP MethionineHomocysteineHomocysteineHomocysteineHomocysteine Dihydrofolate B2, B3, B6! monohydrofolate dihydrofolate B2, B3, B6! Cytosine 5-Methylcytosine Methyl Group DNA Methyltransferase Gene Switched “on” TRANSCRIPTION Gene Switched “off” NO TRANSCRIPTION HACETTEPE MODEL
- 13. B12 Folates THF 5-MeTHF MTHFR Methionine Homocysteine Homocysteine Methyltransferase SAM SAH Adenosyl Homocysteinase Methionine Adenosyl Transferase Cytosine 5-Methylcytosine Methyl Group DNA Methyltransferase Gene Switched “on” TRANSCRIPTION Gene Switched “off” NO TRANSCRIPTION
- 14. B12 5,10-methylene tetrahydrofolate THF 5-MeTHF Methionine Homocysteine Methionine Synthase SAM SAH Adenosyl Homocysteinase Methionine Adenosyl Transferase Cytosine 5-Methylcytosine Methyl Group DNA Methyltransferase Gene Switched “on” TRANSCRIPTION Gene Switched “off” NO TRANSCRIPTION Cystathionine Cystathionine Synthase B6 B2MTHFR Nucleic Acid Synthesis
- 15. C T G CT3’ 5’ C G G CT3’ 5’ RNA Polimeraz C T G CT3’ 5’ Mutasyon Genetik Etki RNA Polimeraz Mutasyon Yok DNA Dizisi Normal Epigenetik Etki RNA Polimeraz
- 16. MethionineHomocysteine Methionine Synthase B12 Methyltetrahydrofolate (active folic acid) Tetrahydrofolate Methylenetetrahydrofolate (dietary folic acid) MTHFR dUMP dTMP DNA-Thymine Cysteine and Propionyl-CoA B6 Cystathionine b-Synthase SAM (S-Adenosyl-L-methionine) SAH (S-Adenosyl-L-homocysteine) ATP MethionineHomocysteineHomocysteineHomocysteineHomocysteine Dihydrofolate B2, B3, B6! monohydrofolate dihydrofolate B2, B3, B6! Cytosine 5-Methylcytosine Methyl Group DNA Methyltransferase Gene Switched “on” TRANSCRIPTION Gene Switched “off” NO TRANSCRIPTION HACETTEPE MODEL