Thrombophilia

Thrombophilia disease

What is the Thrombophilia disease? Thrombophilia refers to a group of disorders characterized by an increased tendency of blood to clot. This multifaceted affliction may manifest as either hereditary or acquired in an individual. Various genetic components, such as the mutation of factor V Leiden, the deficiency in antithrombin III, protein C or S, the insufficiency in glycoprotein rich in histidine, and thrombophilia associated with prothrombin, have the potential to induce thrombophilia in the affected individual. Among the conditions that may instigate the emergence of this disorder in an individual (in the case of an acquired condition) are instances such as heparin-induced thrombocytopenia, antiphospholipid antibody syndrome, neoplasia, utilization of oral contraceptives, obesity, smoking, and surgery. Additional factors and risk factors that heighten the risk of thrombophilia in diverse individuals encompass:

Pregnancy
Having cancer, types of diabetes, heart problems
HIV infection
Immobility of the person for a long time
Overweight and obesity
Receiving hormonal drugs containing estrogen
Increasing age
Having a family history of blood clotting

Thrombophilia, in general, is correlated with the susceptibility to deep venous thrombosis or venous thromboembolism, which may occasionally manifest in atypical sites such as retinal vessels and cerebral vessels. Thrombosis, a condition characterized by the obstruction of bodily vessels due to the formation of a blood clot, gives rise to various manifestations including swelling and pain in the lower extremities, chest discomfort, and unilateral numbness.

Symptoms of thrombophilia

The clinical presentation of thrombophilia varies between individuals and is contingent upon factors such as the size and location of the formed clot, as well as the resultant disorders. Blood clots frequently develop within the microvasculature of the body, particularly in organs like the lungs, brain, hands and feet. Consequently, individuals may exhibit symptoms of thrombophilia, encompassing:

Formation of clots in the lungs and embolism

Severe pain in the chest and its surroundings
Sudden breathing problems during physical activity or rest

Clot formation in the heart and heart attack

Angina or chest pain
Dizziness
Fainting
Respiratory problems

Clot formation in the brain or neck

Stroke (Transient ischemic attack (TIA))
Speaking unintelligibly
Feeling weak or unable to control the muscles on one side of the body

Clot formation in the abdomen and mesenteric ischemia

Nausea and vomiting
Feeling of pain in the abdomen and stomach area, especially after eating
Bloody diarrhea
Having a fever
Flatulence

Clot formation in hands and feet

Pain in the area of clot formation
Swelling due to fluid accumulation
Tingling or numbness with pain
Blistering or ulceration

The types of thrombophilia and their causes

Various forms of thrombophilia exist, and the subsequent discussion will focus on the most prevalent ones.

Factor V Leiden

This particular condition represents the most common type of thrombophilia. Factor V Leiden (FVL) denotes a genetic disorder pertaining to blood coagulation, characterized by an impaired anticoagulant response to APC, which stands for activated protein C. APC functions as a natural anticoagulant protein, with its primary role being the inhibition of pro-coagulant factors Va and VIII, thereby reducing the production of thrombin. Factor V Leiden counteracts factor Va by cleaving it from three distinct regions containing arginine (R 306, R 506, and R 679).

Cause

The term “factor V Leiden” refers to a specific genetic mutation, resulting in the substitution of guanine with adenine at position 1691 in the factor V or F5 gene. This mutation leads to resistance against APC. Individuals carrying this mutation have a heightened propensity to develop deep vein thrombosis (DVT), a type of blood clot that can obstruct blood vessels. Women with this mutation face an increased risk of recurrent miscarriages or miscarriages occurring in the second or third trimester. Although certain studies have reported an association between the factor V Leiden mutation and other pregnancy complications, such as pre-eclampsia (pregnancy-related high blood pressure), slowed fetal growth and premature separation of the placenta from the uterine wall, the relationship between this mutation and these complications remains unconfirmed.

Most women with FVL thrombophilia experience normal pregnancies. The inheritance pattern of this mutation follows an autosomal dominant model and the frequency of the heterozygous mutation outweighs that of the homozygous type. Two methods are available for detecting this mutation: genotyping based on DNA replication and testing the functional resistance of FVL to APC or APC-R. Currently, most molecular laboratories employ PCR-based methods to amplify genomic DNA and subsequently conduct genotyping and hybridization with probes to detect this mutation. While DNA tests offer greater accuracy and sensitivity, some laboratories still utilize the APC-R functional test. If abnormal results are observed, confirmation through DNA testing is recommended. The APC-R test is more cost-effective and also capable of detecting APC resistance caused by factors other than the mutation. However, in cases involving lupus or a family history of thrombophilia, DNA-based methods are suggested.

Other names of thrombophilia disease

APC resistance, Leiden type
Hereditary resistance to activated protein C

Protein C deficiency

Protein C and S are two varieties of vitamin K-dependent glycoproteins and are synthesized within the hepatic organ. The activated form of protein C, also known as APC (Activated form of Protein C), functions as an inherent anticoagulant within the bloodstream. In conjunction with the PS cofactor, it effectively reduces the production of thrombin by inhibiting factors Va and VIIIa. The occurrence of a protein C mutation is a relatively uncommon genetic ailment that can lead to the formation of minute blood clots within the corporeal system.

Cause

The mutation linked to this form of thrombophilia becomes apparent within the PROC gene, which manifests itself in two distinct manifestations. The first is mild in nature and follows an autosomal dominant inheritance pattern, while the second is severe and adheres to an autosomal recessive inheritance pattern. The mild variant entails the mutation of only one PROC gene, whereas the severe variant involves the mutation of both genes.

Other names of this disease

Hereditary thrombophilia due to protein C deficiency
PROC deficiency

Protein S deficiency

Protein S deficiency is an inherent disorder that plays a multifaceted role in the processes of blood coagulation, inflammation and apoptosis. This particular protein acts as a serine protease, facilitating the functioning of active protein C or APC in relation to factors F5a and F8a. Any impairment in this process can result in the formation of blood clots within the vasculature.

Cause

This anomaly arises due to a mutation found within the PROS1 gene, which encodes protein S. Individuals who possess a mutation within one of the PROS1 genes will experience symptoms of the mild variant, whereas the presence of the mutation in both genes will result in more severe symptoms of the disease. The inheritance pattern for this affliction is autosomal dominant in nature.

Other names of this disease

Hereditary thrombophilia due to protein S deficiency

Prothrombin gene mutation

Prothrombin, also known as factor II, serves as the precursor to thrombin within the coagulation cascade of blood. This particular protein exhibits a range of activities, encompassing anticoagulant, antifibrinolytic, and procoagulant functions. Mutations occurring in the gene encoding this protein can lead to a multitude of complications and imbalances within the homeostasis pathway.

Cause

The G20210A mutation, situated in the 3′ UTR region of the prothrombin gene, stands as a paramount mutation observed within this gene, and is correlated with an escalated susceptibility to deep vein thrombosis. The PGM mutation follows factor V Leiden as the second most prevailing genetic alteration responsible for hereditary thrombophilia. Specifically, this mutation manifests as a point mutation (G˃A) within the non-coding segment of the gene at position 20210. As a result, gene expression is heightened, subsequently increasing the quantity of prothrombin protein.

In the heterozygous state, this elevation amounts to approximately 25-30%, while in the homozygous state, the increase reaches 60-70%. Prothrombin represents the primary factor in thrombin production and an augmentation in thrombin levels amplifies the risk of thrombosis. The PGM mutation adheres to an autosomal dominant inheritance pattern, with the heterozygous variation prevailing to a much greater extent than the homozygous variation. DNA genotyping methods, reliant on PCR reaction, facilitate the detection of the PGM mutation.

Other names of this disease

Hyperprothrombinemia
Prothrombin G20210A Thrombophilia

Antiphospholipid syndrome

Antiphospholipid syndrome (APS), also known as Hughes syndrome, is a hereditary disorder that pertains to the immune system and heightens the likelihood of blood clots within the blood vessels. Within this disorder, the immune system produces anomalous antibodies referred to as antiphospholipid antibodies. These particular proteins are attached to lipid molecules or phospholipids and increase the probability of blood coagulation. Females afflicted by this syndrome are at greater peril for complications during pregnancy, which encompass elevated blood pressure (known as pre-eclampsia), insufficient placental function, preterm birth or even miscarriage. One of the most consequential complications of the phospholipid syndrome is the depletion of platelets (thrombocytopenia), the insufficiency of erythrocytes and their untimely breakdown. Suffering from the phospholipid syndrome is one of the factors that contributes to the emergence of thrombosis and disrupts blood supply to tissues. The majority of individuals with antiphospholipid syndrome also contend with other autoimmune disorders, most notably lupus.

Cause

The exact cause of this disease is not known.

Other names of this disease

Anti-phospholipid syndrome
Antiphospholipid antibody syndrome
Hughes syndrome

Thrombophilia diagnosis methods

Currently, several molecular methods are available for the diagnosis of thrombocytosis and FVL and PMG mutations based on DNA amplification and PCR reactions. These methods require DNA extraction, restriction enzymes, agarose or acrylamide gel electrophoresis, fluorescent probes, capillary electrophoresis and real-time analysis. Below are common methods in the field of thrombocytosis diagnosis.

RFLP

The main method for detecting FVL and PMG mutations is the use of RFLP (restriction fragment length polymorphism) technology. DNA is amplified using a PCR reaction and the amplified fragments are digested with restriction enzymes. Finally, the results are separated by agarose gel electrophoresis as bands of various sizes, allowing the differentiation of heterozygous, homozygous and normal alleles. The efficiency of RFLP is increased by performing it in a multiplexed manner and testing two or more mutations simultaneously in one tube.

ARMS-PCR

Among other practical methods in the discussion of the diagnosis of thrombocytosis, one can mention the ARMS-PCR technique (amplification refractory mutation system). It is one of the most accurate tools in the field of genetic disease diagnosis today. This technique is utilized to identify single nucleotide mutations (SNP) or small deletions. The basis of this method is to use PCR primers that are specific for a particular sequence and to precisely connect the 3-end of the primer to the template strand that is amplified by PCR. In this method, amplification of the desired fragment occurs if an allele with the target sequence is present in the genome. When detecting point mutations using ARMS, the presence or absence of mutations can be analyzed by designing two types of complementary primers for the mutant allele and the normal allele, performing PCR using electrophoresis and observing the bands.

The accuracy of genetic tests for detecting FVL and PGM mutations exceeds 99%. DNA-based molecular methods offer the advantage of detecting mutations independently of the phenotype. In contrast to phenotypic and performance-based tests, these methods provide explicit and unambiguous results. Mutations in AT, PC and PS result in a reduction in the quantity or functionality of coagulation inhibitory proteins. These mutations follow an autosomal dominant inheritance pattern and arise from various genetic alterations, including missense, nonsense, splice-site, duplication, deletion and addition. Typically, the measurement of protein quantity or the assessment of protein function is employed through Immunoassay and Chromogenic assay methods to identify such mutations.

REAL-TIME PCR

The Real-Time PCR method is a highly accurate diagnostic tool for thrombophilia. It utilizes TaqMan probes to identify mutations associated with the disease. TaqMan technology relies on the 5′-3′ exonuclease activity of heat-stable Taq-DNA polymerase, along with allele-specific probes that are labeled with a fluorescent reporter dye at the 5′ end and a quencher at the 3′ end. During PCR, when the probe hybridizes with the complementary allelic sequence, the reporter dye is cleaved and separated from the quencher, generating an allele-specific fluorescent signal. To diagnose thrombophilia using Real-Time PCR, DNA must first be extracted from the patient’s blood sample. Then, specific probes designed for mutations related to this disease (F5 c.1691G>A) (p.R506Q) and (F2 c.20210G>A) should be tested.

Thrombophilia treatment

Until a blood clot forms in an individual, there is currently no specific treatment available for thrombophilia. The complications associated with clot formation vary depending on the size and location of the clot. For women who have thrombophilia and take birth control pills, doctors often prescribe pills that solely contain progesterone and do not contain estrogen. Individuals with antiphospholipid syndrome are typically prescribed anticoagulants like warfarin, along with recommendations to prevent complications. In general, modifying one’s lifestyle is the most effective way to prevent blood clot formation in individuals prone to this condition. Some methods that have proven to be effective in preventing clot formation include maintaining proper mobility throughout the day, staying physically fit to prevent weight gain, engaging in regular exercise and controlling fat and salt intake.