The mutation in heterozygosity increases the probability of thrombosis by 3 times. The mutation in homozygosity increases the probability of thrombosis by 18 times, while in smokers by 50%. [PMID 14996674]. Also, this particular mutation is associated with the severe form of preeclampsia. The risk of thrombosis among heterozygotes is 1 in 500 pregnancies [PMID 10666427]

The HR2 polymorphism is considered a mild risk factor for venous thrombosis. The risk for heterozygotes increases by 1.8 times regardless of the presence of other risk factors for thrombophilias. Compound heterozygotes for the HR2 polymorphism and the FactorVLeiden mutation have an increased possibility of venous thrombosis. [PMID 11848454]

Homozygotes for the C677T mutation account for 11% of the Caucasian population. This particular mutation in homozygosity may cause hyperhomocysteinemia in case of dietary folate deficiency, and has been associated with a 3-time increased risk for early cardiovascular disease in the presence of other risk factors. Hyperhomocysteinemia has been associated with the severe form of preeclampsia. Concerning heterozygotes, no clear clinical phenotype has been described. [PMID 8554066]. The T allele has also been characterized as an independent hypertension risk factor[PMID 17726486].

The mutation does not seem to affect the function of the MTHFR protein, therefore homocysteine levels are not altered in the presence of this particular mutation. Compound heterozygotes for the C677T and A1298C mutations show a similar clinical phenotype to homozygotes for the C677T mutation, with higher homocysteine levels and reduced plasma ferric acid levels. Compound heterozygotes are also 2 times more likely to develop neural tube syndrome [PMID 9545395]

The G20210A mutation in the prothrombin gene exists in 2-3% of the Caucasian population and has been described in 6% of patients with a thromboembolic event. The mutation has been associated with a 4-fold increased risk of myocardial infarction in women, while among men the risk is increased by 1.5-fold [PMID 9531249]. This particular mutation in heterozygosity was shown to be the most common among patients with first-trimester miscarriages [PMID 11506076]

The -455G​​>A mutation in heterozygosity or homozygosity has been associated with increased levels of fibrinogen in the blood, which may cause thrombotic episodes. This risk increases especially in chronic smokers and hypertensives as well as in people with small diameter arteries. Increased levels of fibrinogen have been associated with vascular episodes, specifically ischemic stroke. [PMID: 19143925]

Factor XIII or fibrin stabilizing factor is an enzyme of the coagulation system, which serves to stabilize the fibrin network. The Val34Leu polymorphism appears to exert a protective effect against myocardial infarction and to reduce the risk of thrombosis, especially in the case of elevated b-fibrinogen levels. A complete lack of factor XIII is very rare and can cause severe bleeding tendency. The frequency of occurrence is 1 / 1000000. [PMID 17393027] The above polymorphism in combination with the 4G/4G genotype is the most common polymorphism among patients with a history of venous thrombosis and/or a history of miscarriage. [PMID: 18803625] In particular, heterozygosity for the FXIII (V34L) polymorphism combined with the 4G/4G genotype or homozygosity for FXIII (V34L) have been mentioned as a risk factor for six-month miscarriages due to the involvement of FXIII and PAI factors -1 in the creation of the fibrin network during implantation and stabilization of the trophoblast in the endometrium. [PMID: 16938111]

The 4G/4G genotype has been associated with an increased plasma PAI-1 concentration[PMID:258825] and the 5G/5G genotype has been associated with a low plasma PAI-1 gathering. The 4G/5G genotype is associated with normal plasma PAI-1 levels. In the case of increased gathering, the probability of narrowing of the coronary arteries is increased by 70%. [PMID:22011808] The 4G/4G genotype has been shown to be an independent factor in the occurrence of coronary artery thrombosis and atherosclerosis. [PMID:22011808] The 5G/5G genotype has been associated with an increased likelihood of abdominal aortic aneurysms. [PMID:10805895] The 4G/4G genotype has emerged as a risk factor for the occurrence of recurrent miscarriages as mentioned before.

The 5G/5G genotype combined with the presence of the PROTHROMBIN G20210A mutation in heterozygosity appears to contribute to the acceleration of the process leading to the onset of severe preeclampsia.[PMID: 15842353]

High plasma levels of plasminogen activator inhibitor-1 (PAI-1), which is the main inhibitor of fibrinolysis, have been associated with an increased risk of coronary heart disease. In addition, elevated levels of PAI-1 are a common feature of metabolic syndrome and predispose to diabetes mellitus. Homozygosity for this mutation in combination with the 4G allele of PAI-1 -675 increases the risk of polycystic ovary syndrome by 2.5 times [PMID 19856137] Homozygotes and heterozygotes in combination with the 4G allele of PAI-1 -675 also have an increased risk of developing coronary artery disease[PMID 16424345]

GPIIIa (HPA) is a polymorphic antigen on the platelet's surface. The b/b genotype has been associated with the onset of myocardial infarction at a young age (​​<55 years) as well as with an increased risk of coronary artery thrombosis after cardiac procedures with the use of stents. The b allele and the 4G allele of the PAI-1 gene combined to increase the possibility of myocardial infarction by 4 times in women and by 6 times in men [PMID 9700201]. Heterozygotes for the b allele appear to be resistant to the action of anti-thrombotic drugs, e.g. administration of aspirin. [PMID 11723016]

Apolipoprotein B (ApoB) is one of the apolipoproteins involved in lipid metabolism. The mutation at position 3500 leads to a reduced binding capacity between the LDL-ligand and the LDL-receptor and predisposes to the development of hyperlipidemia and early atherosclerosis. It has been reported that the risk of early coronary disease in heterozygous carriers of the mutation is equivalent to that of patients with familial hypercholesterolemia. At the age of 50, approximately 40% of men and 20% of women who carry the above mutation in heterozygosity develop coronary artery disease [PMID 1466657]

Angiotensins are peptides, that function as vasoconstrictor agents. Individuals, that carry the D/D genotype have twice as high levels of angiotensin in the blood compared to individuals, that carry the I/I genotype, and individuals with the I/D genotype have intermediate levels. [PMID: 1313972] The D/D genotype has been associated with an increased risk of hypertension during pregnancy, as a result of mild preeclampsia. [PMID: 22086840] Also, the D/D genotype appears to increase the risk of developing nephropathy in patients with type 2 diabetes. [PMID: 22385293] Contemporaneous presence of the MTHFR 1298C allele appears to increase the above risk. [PMID: 21942443] At the same time, the D/D genotype increases the risk of a hypoglycemic episode by 2 times. [PMID: 21289265]

GPI glycoprotein is a platelet collagen receptor. The 807 C/T polymorphism of the GPIa gene (ITGA2) has been associated with increased expression of GPIa/IIa receptors which appears to play a role in thrombosis. The T allele has been associated with a 1.6-fold increased risk of myocardial infarction in individuals younger than 62 years old. In people younger than 49 years, the risk of myocardial infarction increases by 2.6 times.[PMID 10194421]

The ApoE protein plays a key role in the metabolism of lipoproteins and cholesterol. The E2 isoform has been associated with hyperlipoproteinemia type III (HLPIII). The E2/E2 genotype is found in 1-4% of patients with type III hyperlipoproteinemia, while the E2/E3 and E3/E4 genotypes are rarely found in these patients. [PMID: 7175379] has been associated with an increased risk of atherosclerotic plaque formation and the occurrence of coronary artery disease. The E3 isoform is found in 64% of the population and is phenotypically associated with normal lipoprotein metabolism. The E4 isoform has been associated with atherosclerosis and a history of Alzheimer's disease. [PMID: 8346443] The E2 allele appears to exert a protective effect on the onset of Alzheimer's disease. [PMID: 7910910]

High levels of plasminogen inhibitor type 2 are found in the trophoblast, indicating a possible role in placental maintenance and/or fetal development, which declined significantly during the last 2 weeks of gestation. [PMID: 12786801] Haplotype A, which includes the Ser413 allele, has been associated with an increased risk of myocardial infarction. [PMID: 14653443]

This SNP has been associated with pre-eclampsia and heart disease. Heterozygotes have a 2-fold increased risk of pre-eclampsia (hypertension due to pregnancy) and further complications [PMID 16059745]. Homozygotes have a 1.5-fold increased risk for ischemic heart attack [PMID15007011]

People who have the H3 haplotype have a 1.8-fold increased risk for thrombosis. The H3 haplotype, which has been associated with increased plasma Sepcr levels, is a candidate risk factor for venous thrombosis[PMID 14576048]. Individuals heterozygous for the prothrombin 20210A mutation, who also have the H3 haplotype in heterozygosity, combined with elevated Sepcr levels (​​>147ng/ml) and prothrombin time​​>129%, have a 9-fold increased risk for thrombosis​​[PMID 18403391]

Homozygotes for the (C/C) genotype have a 0.61-fold reduced risk for thrombosis. Those who have the H1 haplotype in homozygosity have higher APC levels and thus a reduced risk for venous thrombosis[PMID 15116250] Homozygosity for this mutation reduces the risk for venous thrombosis in individuals heterozygous for the FVLeiden [PMID 16113830]mutation.

Polymorphisms in the Lp(a) gene locus appear to predispose to coronary heart disease (CHD), cerebrovascular disease (CVD), early atherosclerosis, thrombosis, and stroke. The presence of the A5673G mutation in heterozygosity/homozygosity is associated with increased levels of lipoprotein A Lp(a). People who have the above polymorphism appear a 2-fold increased risk of cardiovascular disease, but they seem to benefit from the administration of aspirin (100mg every other day)[PMID 18775538].