Genes predisposing to thrombosis

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<div class="col_three_fifth topmargin nobottommargin"><div class="heading-block heading-block-right"><h3 class="hun">Tromb&oacute;zisra hajlamos&iacute;t&oacute; g&eacute;nek</h3><h3 class="eng">Genes predisposing to thrombosis</h3><span style="font-family: 'Raleway', sans-serif;"></span></div><p class="text-justify hun">A v&eacute;n&aacute;s tromb&oacute;zis egy s&uacute;lyos k&ouml;vetkezm&eacute;nyekkel j&aacute;r&oacute; betegs&eacute;g, amely multifaktori&aacute;lis, vagyis kiv&aacute;lt&oacute; okai k&ouml;zt genetikai &eacute;s k&ouml;rnyezeti t&eacute;nyezők egyar&aacute;nt szerepelnek. Egy gyakori genetikai elv&aacute;ltoz&aacute;s, az &uacute;n. <strong>Leiden-mut&aacute;ci&oacute;</strong> (másnéven aktivált protein C rezisztencia) egy ilyen, genetikai eredetű véralvadási zavart okoz. Az öröklődő trombózishajlam 80%-ban ehhez az elváltozáshoz köthető. A mutáció miatt a betegeknek fokozottan alvadékony a vére, így trombózisra - azaz vérrögképződés okozta érelzáródásra - hajlamosak.</p><p class="text-justify eng">Venous thrombosis is a multifactorial disease with serious consequences, that is, it is caused by a combination of genetic and environmental factors. The <strong>Leiden mutation</strong> (or activated protein C resistance) is a frequent genetic alteration causing blood clotting disorder. Hereditary predisposition to thrombosis can be linked to this alteration in 80% of the cases. Due to the mutation, the patients’ blood have an increased tendency to coagulate, resulting in a predisposition to thrombosis - the blocking of a blood vessel by a clot.</p><p class="text-justify hun"><strong>Az elv&aacute;ltoz&aacute;s igen gyakori, Magyarorsz&aacute;gon a n&eacute;pess&eacute;g 10%-a hordozza</strong>. Ez azt jelenti, hogy a gén két példánya közül csak az egyiken van mutáció, azonban a trombózisra való hajlam már ekkor is 8-szorosára emelkedik. Ha mindkét génkópiánkon megtalálható a hibásodás, a kockázat 80-szorosára növekszik, ha semmilyen más további kockázati tényező nem áll fenn.</p><p class="text-justify eng"><strong>This alteration is very frequent in Hungary: 10% of the population carries it</strong>. This means that only one of the two copies of the gene harbours the mutation; still, the predisposition to thrombosis increases already 8-fold. If both copies of the gene carries the mutation, the risk increases 80-fold, provided there are no further risk factors.</p><p class="text-justify hun">Az ismeretlen ok&uacute; tromb&oacute;zisok 20%-&aacute;ban, a terhess&eacute;g alatt jelentkező tromb&oacute;zisoknak pedig mintegy 60%-&aacute;ban kimutathat&oacute; a mut&aacute;ci&oacute;. Tov&aacute;bb&aacute; az ism&eacute;tlődő abortuszokkal, illetve terhess&eacute;gi komplik&aacute;i&oacute;kkal is &ouml;sszef&uuml;gg&eacute;sben lehet a genetikai elv&aacute;ltoz&aacute;s.</p><p class="text-justify eng">The mutation can be detected in 20% of the thrombosis cases of unknown cause and in 60% of the cases of thrombosis developing during pregnancy. Furthermore, this genetic alteration may be associated with recurrent miscarriages and complications of pregnancy.</p><div class="thumbnail"><img src="images/bandage.jpg"><div class="caption"><h4></h4><p class="text-justify hun">A <strong>tromb&oacute;zishajlamot</strong> a genetikai okok mellett környezeti és életmódbéli tényezők is <strong>n&ouml;velik</strong>, ilyenek például a <strong>hormon&aacute;lis fogamz&aacute;sg&aacute;tl&oacute;k szed&eacute;se, az elh&iacute;z&aacute;s, a doh&aacute;nyz&aacute;s, a cukorbetegs&eacute;g, vagy a mozg&aacute;sszeg&eacute;ny &eacute;letm&oacute;d</strong>. De a <strong>v&aacute;rand&oacute;ss&aacute;g</strong>, mint természetes állapot is jelentősen növelheti a rizikót, a trombózis pedig a magzati életet is veszélyeztető következményekkel jár. Ilyen esetben a nőgyógyásznak mindenképpen tudnia kell a mutáció jelenlétéről, mert a terhesség alatt szigorúan tilos a K-vitamin antagonisták adása.</p><p class="text-justify eng"><strong>The likelihood of thrombosis</strong>, besides the genetic causes, is also <strong>increased</strong> by environmental and lifestyle factors such as the <strong>use of hormonal contraceptive pills, obesity, smoking, diabetes, or sedentary life style</strong>. But pregnancy, a natural condition, may also significantly increase the risk, and thrombosis may even have consequences that endanger the foetus. In such cases, the gynaecologist should be aware of the presence of the mutation, because administration of vitamin K antagonists is strictly contraindicated during pregnancy. </p></div></div><div class="heading-block heading-block-right"><h3></h3><span class="hun" style="font-family: 'Raleway', sans-serif;">Leiden-mut&aacute;ci&oacute;</span><span class="eng" style="font-family: 'Raleway', sans-serif;">Leiden mutation</span></div><p class="text-justify hun">A <strong>Leiden-mut&aacute;ci&oacute;</strong> (másnéven: trombofília, aktivált protein C rezisztencia) egy <strong>genetikai eredetű v&eacute;ralvad&aacute;si zavar</strong>. A mutáció miatt a véralvadást elősegítő faktorok bomlásának lassulása következik be, emiatt a betegeknek fokozottan alvadékony a vére, így trombózisra - azaz vérrögképződés okozta érelzáródásra - hajlamosak. Az öröklődő trombózishajlam <strong>80%-ban</strong> ehhez az elváltozáshoz köthető. A Leiden-mutáció esetében a trombózishajlam már heterozigóta formában (amikor a gén két példánya közül csak az egyiken van mutáció) is megnyilvánul, homozigóta formában (azaz, ha mindkét példányon megtalálható) pedig sokkal kifejezettebb. Az egészséges magyar népesség 10%-a heterozigóta a Leiden-mutációra, a homozigóták részaránya néhány ezrelék. A mutációt heterozigóta formában hordozó személyeknek kb. 8-szor, a homozigótáknak pedig kb. 80-szor akkora a kockázata mélyvénás trombózisra, mint az átlag népességnek, ha semmilyen más további kockázati tényező nem áll fenn.</p><p class="text-justify eng">The <strong>Leiden mutation</strong> (synonyms: thrombophilia, activated protein C resistance) is a blood clotting disorder of genetic origin. Due to the mutation, the degradation of factors enhancing blood clotting slows down, and thus the patients’ blood have an increased tendency to coagulate, resulting in a predisposition to thrombosis - the blocking of a blood vessel by a clot. Hereditary predisposition to thrombosis can be linked to this alteration in <strong>80% of the cases</strong>. In the Leiden mutation, the predisposition to thrombosis is already apparent in the heterozygous form (when only one of the two copies of the gene carries a mutation) and is even more explicit in homozygous form (when the mutation is present in both copies). 10% of the healthy Hungarian population is heterozygous for the Leiden mutation, and a few per thousand are homozygous. Individuals carrying the mutation in a heterozygous form have an approximately 8-fold higher risk, while those carrying it in a homozygous form have an approximately 80-fold higher risk of deep vein thrombosis compared to the average population, provided there are no further risk factors.</p><p class="text-justify hun">Fontos, hogy fiatal korban jelentkező, m&aacute;ssal nem magyar&aacute;zhat&oacute; &eacute;s/vagy ism&eacute;tlődő tromb&oacute;zis kapcs&aacute;n minden esetben t&ouml;rt&eacute;njen meg a Leiden-mut&aacute;ci&oacute; kiz&aacute;r&aacute;sa. Amennyiben a betegnek vannak gyermekei vagy &eacute;lnek a sz&uuml;lei, a vizsg&aacute;latot n&aacute;luk is el kell v&eacute;gezni.</p><p class="text-justify eng">It is essential that in cases of thrombosis occurring at young age with no known cause and/or in cases of recurrent thrombosis testing for the Leiden mutation should by all means be performed. If the patient has children or his/her parents are alive, they should also be tested.</p><div class="heading-block heading-block-right"><h3></h3><span class="hun" style="font-family: 'Raleway', sans-serif;">Protrombin mut&aacute;ci&oacute;</span><span class="eng" style="font-family: 'Raleway', sans-serif;">Prothrombin mutation</span></div><p class="text-justify hun" style="font-size: 15px;">A <strong>protrombin vagy II. alvad&aacute;si faktor mut&aacute;ci&oacute;</strong>ja az örökletes trombózishajlam második leggyakoribb oka. Az elváltozás miatt emelkedett protrombin szint alakul ki, ennek következtében a véralvadási rendszer aktivitása fokozódik, így nő a trombózis kialakulásának esélye. Ez a génelváltozás az átlagos népesség 2%-át érinti. A mélyvénás trombózis kockázatát mintegy 3-szorosára növeli. A mutációt heterozigóta formában hordozó nőkben a szívinfarktus kialakulásának kockázata négyszer nagyobb, mint a mutációt nem hordozókban, és a kockázat fokozódik, ha más rizikótényező (dohányzás, fogamzásgátló gyógyszer) is fennáll. Homozigóta formában nagyon ritka, de egyes tanulmányok szerint az ismétlődő vetélések hátterében is ez a mutáció állhat.</p><p class="text-justify eng" style="font-size: 15px;">Mutation of <strong>prothrombin or coagulation factor II</strong> is the second most common cause of hereditary disposition to thrombosis. Due to the alteration, the prothrombin level is elevated and, as a result, the activity of the coagulation system increases leading to a higher probability of thrombosis. This gene alteration affects 2% of the average population and increases the risk of deep vein thrombosis approximately 3-fold. The risk of developing myocardial infarction is 4-fold higher in women carrying the mutation in a heterozygous form compared to those who do not carry it, and it is further increased by other risk factors (smoking, contraceptive pills). The homozygous form of the mutation is very rare but, according to some studies, this mutation may be responsible for recurrent pregnancy losses. </p><p class="text-justify hun">A mut&aacute;ci&oacute; vizsg&aacute;lata javasolt viszonylag fiatal korban előfordul&oacute; agyi &eacute;relz&aacute;r&oacute;d&aacute;s (sz&eacute;l&uuml;t&eacute;s), illetve nőkn&eacute;l sz&iacute;vinfarktus bek&ouml;vetkez&eacute;se eset&eacute;ben, ism&eacute;telt vet&eacute;l&eacute;seket k&ouml;vetően, illetve amennyiben igazoltan van a csal&aacute;dban protrombin mut&aacute;ci&oacute;t hordoz&oacute; rokon.</p><p class="text-justify eng">Screening for the mutation is recommended in cases of brain blood vessel blockage (stroke) at a young age, in women developing myocardial infarction, after recurrent pregnancy losses, or if there is a verified prothrombin mutation-carrier relative in the family.</p><div class="heading-block heading-block-right"><h3></h3><span class="hun" style="font-family: 'Raleway', sans-serif;">MTHFR mut&aacute;ci&oacute;</span><span class="eng" style="font-family: 'Raleway', sans-serif;">MTHFR mutation</span></div><p class="text-justify hun" style="font-size: 15px;">Az <strong>MTHFR (metil&eacute;ntetrahidrofol&aacute;t redukt&aacute;z)</strong> gén mutációja örökletes módon fokozza a vér homocisztein szintjét. A vér emelkedett homociszteinszintje a népesség 5-10%-ában fordul elő, a trombózis kockázata ilyenkor a normális homociszteinszintű személyekéhez képest csaknem 3-szoros. Ez az artériás és vénás trombózis, valamint terheseknél a magzati elhalás ismert kockázati tényezője, továbbá fokozza a magzati velőcsőzáródási rendellenesség kockázatát. Az emelkedett homocisztein szint (hiperhomociszteinémia) kialakulásának nagyobb a valószínűsége, ha csökkent a szervezet folsav ellátottsága, így fokozott folsav bevitellel csökkenthető a vér homocisztein szintje. <strong>A mut&aacute;ci&oacute; vizsg&aacute;lata javasolt emelkedett sz&eacute;rum homocisztein szint eset&eacute;n.</strong></p><p class="text-justify eng" style="font-size: 15px;">Mutation in the <strong>MTHFR (methylenetetrahydrofolate reductase)</strong> gene results in a hereditary elevation of the blood homocysteine level. Elevated blood homocysteine levels, which lead to an almost 3-fold increase in the risk of thrombosis compared to individuals with normal blood homocysteine level, can be found in 5-10% of the population. Elevated homocysteine level is a known risk factor of arterial and venous thrombosis, loss of pregnancy, and neural tube closure defects in the foetus. Lack of folic acid increases the probability of developing elevated homocysteine levels (hyperhomocysteinemia); thus, increased folic acid intake can reduce blood homocysteine levels. <strong>Testing the mutation is recommended in cases of elevated serum homocysteine level. </strong></p><p class="text-justify hun">A mut&aacute;ci&oacute; heterozig&oacute;ta form&aacute;ja eset&eacute;n egy&aacute;ltal&aacute;n nem, vagy csak kis m&eacute;rt&eacute;kben emelkedik a homocisztein koncentr&aacute;ci&oacute;ja a sz&eacute;rumban, azonban homozig&oacute;ta form&aacute;ban ez az emelked&eacute;s m&aacute;r j&oacute;val kifejezettebb. A popul&aacute;ci&oacute;ban a homozig&oacute;ta mut&aacute;ci&oacute; előfordul&aacute;sa viszonylag gyakori, az &aacute;tlagn&eacute;pess&eacute;g 5-15%-&aacute;ban fordul elő.</p><p class="text-justify eng">When the mutation is present in a heterozygous form, the concentration of homocysteine is not or is only slightly elevated in the serum, while this increase is much more explicit in the homozygous form of the mutation. The prevalence of the homozygous mutation in the population is relatively high; it is present in 5-15% of the average population.</p></div><div class="col_two_fifth nobottommargin col_last"><div class="thumbnail thumbnail-FAQ" style="margin-top: 35px !important;"><div class="caption"><h4 class="hun" style="font-size:26px;font-weight: 700;text-transform: uppercase;letter-spacing: 1px">Gyakran ism&eacute;telt k&eacute;rd&eacute;sek</h4><h4 class="eng" style="font-size:26px;font-weight: 700;text-transform: uppercase;letter-spacing: 1px">FREQUENTLY ASKED QUESTIONS</h4></div><div class="col-sm-12"><div class="gyikHead hun">Mikor gyanakodhatok r&aacute;, hogy hordozom a Leiden-mut&aacute;ci&oacute;t? </div><div class="gyikHead eng">When should I suspect that I am carrying the Leiden mutation? </div><div class="gyikBody hun">Fiatal korban jelentkező, ism&eacute;tlődő tromb&oacute;zis eset&eacute;n, ha az m&aacute;ssal nem magyar&aacute;zhat&oacute;. Ha a csal&aacute;dban t&ouml;bbsz&ouml;r előfordult m&aacute;r tromb&oacute;zis, valamint a v&aacute;rand&oacute;ss&aacute;g alatti komplik&aacute;ci&oacute;k is utalhatnak a mut&aacute;ci&oacute; jelenl&eacute;t&eacute;re. </div><div class="gyikBody eng">In case of recurrent thrombosis occurring at young age when there are no other known causes. Several cases of thrombosis in the family and complications of pregnancy may also indicate the presence of the mutation. </div></div><div class="col-sm-12"><div class="gyikHead hun">Mikor gyanakodhatok r&aacute;, hogy hordozom a prothrombin mut&aacute;ci&oacute;t? </div><div class="gyikHead eng">When should I suspect that I am carrying the prothrombin mutation? </div><div class="gyikBody hun">Viszonylag fiatal korban előfordul&oacute; sz&eacute;l&uuml;t&eacute;s, sz&iacute;vinfarktus eset&eacute;n, tov&aacute;bb&aacute; sorozatos vet&eacute;l&eacute;sek k&ouml;vetkezt&eacute;ben. </div><div class="gyikBody eng">In cases of stroke, myocardial infarction at a relatively young age, or recurrent pregnancy losses. </div></div><div class="col-sm-12"><div class="gyikHead hun">Mikor gyanakodhatok r&aacute;, hogy hordozom az MTHFR mut&aacute;ci&oacute;t? </div><div class="gyikHead eng">When should I suspect that I am carrying the MTHFR mutation? </div><div class="gyikBody hun">Ez a mut&aacute;ci&oacute; egy k&oacute;pi&aacute;ban nem n&ouml;veli a tromb&oacute;zis kock&aacute;zat&aacute;t, azonban a mindk&eacute;t k&oacute;pi&aacute;ban mut&aacute;ci&oacute;t hordoz&oacute; egy&eacute;nekn&eacute;l emelkedett homocisztein-szintet eredm&eacute;nyez. Ez pedig hajlamos&iacute;t a tromb&oacute;zisra, valamint a magzati elhal&aacute;st is előseg&iacute;ti. </div><div class="gyikBody eng">This mutation, if carried in one copy, does not increase the risk of thrombosis; however, it leads to elevated blood homocysteine levels in individuals carrying the mutation in both copies of the gene. This predisposes to thrombosis and loss of pregnancy. </div></div><div class="col-sm-12"><div class="gyikHead hun">Fogamz&aacute;sg&aacute;tl&oacute;t szedek, &eacute;rdemes elv&eacute;geznem a tesztet? </div><div class="gyikHead eng">I am taking contraceptive pills; should I have the test done? </div><div class="gyikBody hun">A hormon&aacute;lis fogamz&aacute;sg&aacute;tl&oacute;k k&ouml;zvetetten n&ouml;velik az alvad&aacute;sban r&eacute;szt vevő egyes feh&eacute;rj&eacute;k koncentr&aacute;ci&oacute;j&aacute;t, &iacute;gy n&ouml;velve a tromb&oacute;zis kock&aacute;zat&aacute;t az &aacute;tlag n&eacute;pess&eacute;ghez k&eacute;pest 4-szeres&eacute;re. A fenti mut&aacute;ci&oacute;k ezt a kock&aacute;zatot jelentősen megn&ouml;velik, ez&eacute;rt indokolt a vizsg&aacute;lat elv&eacute;gz&eacute;se. </div><div class="gyikBody eng">Hormonal contraceptive pills indirectly increase the concentration of certain proteins that participate in clotting, thus increasing the risk of thrombosis 4-fold compared to the average population. The mutations above significantly increase this risk, therefore, testing is warranted. </div></div><div class="col-sm-12"><div class="gyikHead hun">Mit tegyek, ha beigazol&oacute;dik, hogy mut&aacute;ci&oacute;t hordozok? </div><div class="gyikHead eng">What should I do if I am found to carry a mutation? </div><div class="gyikBody hun">Ha &Ouml;n a Leiden, vagy Prothrombin g&eacute;nj&eacute;ben mindk&eacute;t k&oacute;pi&aacute;ban mut&aacute;ci&oacute;t hordoz, megfelelően be&aacute;ll&iacute;tott, tart&oacute;s v&eacute;ralvad&aacute;sg&aacute;tl&oacute; szed&eacute;se javasolt, emellett nagyon fontos a megfelelő &eacute;letm&oacute;d. Ez mag&aacute;ban foglalja, hogy: <ul class="iconlist" style="padding-right:40px; padding-left:40px;"><li style="font-family: 'Cairo', sans-serif;font-size: 15px;line-height: 1.8;"><i class="icon-medical-i-cardiology"></i> csökkenti, vagy abbahagyja a dohányzást</li><li style="font-family: 'Cairo', sans-serif;font-size: 15px;line-height: 1.8;"><i class="icon-medical-i-cardiology"></i> fokozott testmozgást iktat be mindennapjaiba</li><li style="font-family: 'Cairo', sans-serif;font-size: 15px;line-height: 1.8;"><i class="icon-medical-i-cardiology"></i> rendszeres orvosi ellenőrzést biztosít</li><li style="font-family: 'Cairo', sans-serif;font-size: 15px;line-height: 1.8;"><i class="icon-medical-i-cardiology"></i> csökkenti a koleszterin-dús ételek fogyasztását</li></ul>Ha Ön mutációt hordoz az MTHFR génjének mindkét kópiájában, ez negatívan befolyásolja a folsav-anyagcserét. Ezért fontos a fokozott folsav-bevitel. </div><div class="gyikBody eng">If you carry mutations in both copies of the Leiden or Prothrombin genes, continuous, well-adjusted anticoagulation therapy is recommended, and an appropriate lifestyle is also essential. This includes: <ul class="iconlist" style="padding-right:40px; padding-left:40px;"><li style="font-family: 'Cairo', sans-serif;font-size: 15px;line-height: 1.8;"><i class="icon-medical-i-cardiology"></i> reducing or stopping smoking </li><li style="font-family: 'Cairo', sans-serif;font-size: 15px;line-height: 1.8;"><i class="icon-medical-i-cardiology"></i> including more physical exercise in your daily routine </li><li style="font-family: 'Cairo', sans-serif;font-size: 15px;line-height: 1.8;"><i class="icon-medical-i-cardiology"></i> having regular medical check-ups </li><li style="font-family: 'Cairo', sans-serif;font-size: 15px;line-height: 1.8;"><i class="icon-medical-i-cardiology"></i> reducing the consumption of food rich in cholesterol </li></ul>If you carry a mutation in both copies of your MTHFR gene, your folic acid metabolism is adversely affected, thus, increased folic acid intake is important. </div></div><div class="col-sm-12"><div class="gyikHead hun">Mit kell tennem a vizsg&aacute;lat elv&eacute;gz&eacute;s&eacute;hez? </div><div class="gyikHead eng">What should I do to have the test done? </div><div class="gyikBody hun">&Ouml;nnek csup&aacute;n fel kell keresnie genetikai tan&aacute;csad&oacute;nkat, aki k&eacute;szs&eacute;ggel seg&iacute;ts&eacute;g&eacute;re lesz abban, hogy a mindh&aacute;rom g&eacute;nt &eacute;rintő vizsg&aacute;lat az &Ouml;n, vagy csal&aacute;dtagja eset&eacute;ben indokolt-e. Amennyiben javasolt a vizsg&aacute;lat elv&eacute;gz&eacute;se, egy egyszerű v&eacute;rv&eacute;tel elegendő hozz&aacute;. </div><div class="gyikBody eng">You only have to contact our genetic counsellor who will be glad to give you advice on whether the test involving the three genes is indicated for you or for a member of your family. </div></div><div class="col-sm-12"><div class="gyikHead hun">Mennyi időn bel&uuml;l sz&aacute;m&iacute;thatok az eredm&eacute;nyre? </div><div class="gyikHead eng">When can I expect to have the result? </div><div class="gyikBody hun">A minta lev&eacute;tel&eacute;t k&ouml;vetően 1 h&eacute;ten bel&uuml;l elk&eacute;sz&uuml;l az eredm&eacute;ny, melyet genetikai tan&aacute;csad&oacute;nk jelez &Ouml;nnek, tov&aacute;bb&aacute; ell&aacute;tja &Ouml;nt az eredm&eacute;ny &eacute;rtelmez&eacute;s&eacute;hez, &eacute;s az esetleges tov&aacute;bbi teendőkh&ouml;z sz&uuml;ks&eacute;ges inform&aacute;ci&oacute;kkal. </div><div class="gyikBody eng">The result is ready within 1week of sample taking; our genetic counsellor will contact you and provide all the information necessary for the interpretation of the result and for the further steps if required. </div></div></div><div class="thumbnail thumbnail-FAQ"><img src="images/verrog.jpg"><div class="caption hun"><h4>Fogamz&aacute;sg&aacute;tl&oacute;k &eacute;s a Leiden-mut&aacute;ci&oacute;</h4><p class="text-justify"><strong>Ha &Ouml;n Leiden mut&aacute;ci&oacute;t hordoz, &eacute;s emellett fogamz&aacute;sg&aacute;tl&oacute;t szed, a tromb&oacute;zis kock&aacute;zata 8-szorosr&oacute;l ak&aacute;r 30-40-szeresre is emelkedhet. Ha &Ouml;nnek mindk&eacute;t all&eacute;lja mut&aacute;ns, fogamz&aacute;sg&aacute;tl&oacute; szed&eacute;se mellett ugyanez a kock&aacute;zat 80-szorosr&oacute;l t&ouml;bb mint 100-szorosra nő.</strong> Ezért a vizsgálat elvégzése javasolt fogamzásgátló használata előtt.</p></div><div class="caption eng"><h4>Contraceptives and the Leiden mutation </h4><p class="text-justify"><strong>If you are carrying a Leiden mutation and you are taking contraceptive pills, then the 8-fold risk may rise to even 30-40-fold. If both of your alleles are mutant, taking contraceptives increases this risk from 80-fold to more than 100-fold</strong> Thus, it is recommended to have the test done before starting to take contraceptive pills.</p></div></div></div><div class="col_three_fifth topmargin nobottommargin trombozis hidden"><div class="heading-block heading-block-right"><h3 class="hun"></h3><h3 class="eng"></h3><span class="hun" style="font-family: 'Raleway', sans-serif;">Tudom&aacute;nyos h&aacute;tt&eacute;r</span><span class="eng" style="font-family: 'Raleway', sans-serif;">Scientific background</span></div></div>

Genes predisposing to thrombosis

Venous thrombosis is a multifactorial disease with serious consequences, that is, it is caused by a combination of genetic and environmental factors. The Leiden mutation (or activated protein C resistance) is a frequent genetic alteration causing blood clotting disorder. Hereditary predisposition to thrombosis can be linked to this alteration in 80% of the cases. Due to the mutation, the patients’ blood have an increased tendency to coagulate, resulting in a predisposition to thrombosis - the blocking of a blood vessel by a clot.

This alteration is very frequent in Hungary: 10% of the population carries it. This means that only one of the two copies of the gene harbours the mutation; still, the predisposition to thrombosis increases already 8-fold. If both copies of the gene carries the mutation, the risk increases 80-fold, provided there are no further risk factors.

The mutation can be detected in 20% of the thrombosis cases of unknown cause and in 60% of the cases of thrombosis developing during pregnancy. Furthermore, this genetic alteration may be associated with recurrent miscarriages and complications of pregnancy.

The likelihood of thrombosis, besides the genetic causes, is also increased by environmental and lifestyle factors such as the use of hormonal contraceptive pills, obesity, smoking, diabetes, or sedentary life style. But pregnancy, a natural condition, may also significantly increase the risk, and thrombosis may even have consequences that endanger the foetus. In such cases, the gynaecologist should be aware of the presence of the mutation, because administration of vitamin K antagonists is strictly contraindicated during pregnancy.

Leiden mutation

The Leiden mutation (synonyms: thrombophilia, activated protein C resistance) is a blood clotting disorder of genetic origin. Due to the mutation, the degradation of factors enhancing blood clotting slows down, and thus the patients’ blood have an increased tendency to coagulate, resulting in a predisposition to thrombosis - the blocking of a blood vessel by a clot. Hereditary predisposition to thrombosis can be linked to this alteration in 80% of the cases. In the Leiden mutation, the predisposition to thrombosis is already apparent in the heterozygous form (when only one of the two copies of the gene carries a mutation) and is even more explicit in homozygous form (when the mutation is present in both copies). 10% of the healthy Hungarian population is heterozygous for the Leiden mutation, and a few per thousand are homozygous. Individuals carrying the mutation in a heterozygous form have an approximately 8-fold higher risk, while those carrying it in a homozygous form have an approximately 80-fold higher risk of deep vein thrombosis compared to the average population, provided there are no further risk factors.

It is essential that in cases of thrombosis occurring at young age with no known cause and/or in cases of recurrent thrombosis testing for the Leiden mutation should by all means be performed. If the patient has children or his/her parents are alive, they should also be tested.

Prothrombin mutation

Mutation of prothrombin or coagulation factor II is the second most common cause of hereditary disposition to thrombosis. Due to the alteration, the prothrombin level is elevated and, as a result, the activity of the coagulation system increases leading to a higher probability of thrombosis. This gene alteration affects 2% of the average population and increases the risk of deep vein thrombosis approximately 3-fold. The risk of developing myocardial infarction is 4-fold higher in women carrying the mutation in a heterozygous form compared to those who do not carry it, and it is further increased by other risk factors (smoking, contraceptive pills). The homozygous form of the mutation is very rare but, according to some studies, this mutation may be responsible for recurrent pregnancy losses.

Screening for the mutation is recommended in cases of brain blood vessel blockage (stroke) at a young age, in women developing myocardial infarction, after recurrent pregnancy losses, or if there is a verified prothrombin mutation-carrier relative in the family.

MTHFR mutation

Mutation in the MTHFR (methylenetetrahydrofolate reductase) gene results in a hereditary elevation of the blood homocysteine level. Elevated blood homocysteine levels, which lead to an almost 3-fold increase in the risk of thrombosis compared to individuals with normal blood homocysteine level, can be found in 5-10% of the population. Elevated homocysteine level is a known risk factor of arterial and venous thrombosis, loss of pregnancy, and neural tube closure defects in the foetus. Lack of folic acid increases the probability of developing elevated homocysteine levels (hyperhomocysteinemia); thus, increased folic acid intake can reduce blood homocysteine levels. Testing the mutation is recommended in cases of elevated serum homocysteine level.

When the mutation is present in a heterozygous form, the concentration of homocysteine is not or is only slightly elevated in the serum, while this increase is much more explicit in the homozygous form of the mutation. The prevalence of the homozygous mutation in the population is relatively high; it is present in 5-15% of the average population.

FREQUENTLY ASKED QUESTIONS

When should I suspect that I am carrying the Leiden mutation?
In case of recurrent thrombosis occurring at young age when there are no other known causes. Several cases of thrombosis in the family and complications of pregnancy may also indicate the presence of the mutation.
When should I suspect that I am carrying the prothrombin mutation?
In cases of stroke, myocardial infarction at a relatively young age, or recurrent pregnancy losses.
When should I suspect that I am carrying the MTHFR mutation?
This mutation, if carried in one copy, does not increase the risk of thrombosis; however, it leads to elevated blood homocysteine levels in individuals carrying the mutation in both copies of the gene. This predisposes to thrombosis and loss of pregnancy.
I am taking contraceptive pills; should I have the test done?
Hormonal contraceptive pills indirectly increase the concentration of certain proteins that participate in clotting, thus increasing the risk of thrombosis 4-fold compared to the average population. The mutations above significantly increase this risk, therefore, testing is warranted.
What should I do if I am found to carry a mutation?
If you carry mutations in both copies of the Leiden or Prothrombin genes, continuous, well-adjusted anticoagulation therapy is recommended, and an appropriate lifestyle is also essential. This includes:
  • reducing or stopping smoking
  • including more physical exercise in your daily routine
  • having regular medical check-ups
  • reducing the consumption of food rich in cholesterol
If you carry a mutation in both copies of your MTHFR gene, your folic acid metabolism is adversely affected, thus, increased folic acid intake is important.
What should I do to have the test done?
You only have to contact our genetic counsellor who will be glad to give you advice on whether the test involving the three genes is indicated for you or for a member of your family.
When can I expect to have the result?
The result is ready within 1week of sample taking; our genetic counsellor will contact you and provide all the information necessary for the interpretation of the result and for the further steps if required.

Contraceptives and the Leiden mutation

If you are carrying a Leiden mutation and you are taking contraceptive pills, then the 8-fold risk may rise to even 30-40-fold. If both of your alleles are mutant, taking contraceptives increases this risk from 80-fold to more than 100-fold Thus, it is recommended to have the test done before starting to take contraceptive pills.