Haemophilia Blood Clot Disorders Biology Essay

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Hemophilia is a group of inherited blood disorders in which the blood does not clot properly. Bleeding disorders are due in part to defective blood vessels, coagulation mechanisms or blood platelets. An affected individual may bleed spontaneously or for longer than a healthy person after injury or surgery. The blood coagulation mechanism is a process which transforms the blood from a liquid into a solid, and involves several different clotting factors. The mechanism generates fibrin when it is activated, which together with the platelet plug, stops the bleeding. When coagulation factors are missing or deficient the blood does not clot properly and bleeding continues. Hemophilia can be divided into two major types: hemophilia A or hemophilia B. 9 out of 10 people who have hemophilia will have type A hemophilia which means the body is missing or has low levels of clotting factor 8. If the person has type B, then they are missing or have low levels of clotting factor 9. Although there are many ways to diagnose hemophilia , there are numerous treatment options one could take , although replacing the clotting factors seems to be the best option available as of yet, as genetic advances continue to make way for better treatments.

Annual incidence of haemophilia is estimated at 1/5,000 male births and the prevalence is estimated to be at 1/12,000. About 400 babies are born with hemophilia each year. The exact number of people living with hemophilia in the United States is not knownbut the current estimate is about 20,000. In the United States, most people with hemophilia are diagnosed at a very young age. Genetic testing and genetic counselling is recommended for families with haemophilia. Prenatal testing is available to pregnant women who may be carriers of the condition. Based on CDC data, the median age at diagnosis is 36 months for people with mild hemophilia, 8 months for those with moderate hemophilia, and 1 month for those with severe hemophilia..

The major signs and symptoms of hemophilia are excessive bleeding and easy bruising. Bleeding can occur on externally or internally. Signs of excessive external bleeding include: bleeding in the mouth from a cut or bite or from cutting or losing a tooth, nosebleeds, heavy bleeding from a minor cut, bleeding from a cut that resumes after stopping for a short time. Signs of internal bleeding include blood in the urine (from bleeding in the kidneys or bladder) and blood in the stool (from bleeding in the intestines or stomach). Internal bleeding in the brain is a very serious complication of hemophilia that can happen after a simple bump on the head or a more serious injury. Many serious complications can also arise from bleeding into various body systems. Hemarthrosis is a bleeding into joint spaces and may be prevalent to those with a more serius from of the disease.

Haemophilia is caused by a malfunction in the X chromosome. To most recessive sex-linked, X chromosome disorders, haemophilia is more likely to occur in males rather than females. Females have two X chromosomes so they are covered by one X, unless in the case of X-inactivation. The F8 gene is responsible for this. The F8 gene is located on the long arm of the X chromosome and is at point q28 (genetics home reference). F8 gene codes for coagulation factor VIII which is an essential for proper clotting to take place. As stated in the genetics home reference hemophilia A, "More than 1,300 alterations in this gene have been identified. Some of these mutations change single DNA building blocks (base pairs) in the gene, while others delete or insert multiple base pairs. The most common mutation in people with severe hemophilia A is a rearrangement of genetic material called an inversion. This inversion involves a large segment of the F8 gene." (genetics home reference) An inversion is when a chromosome breaks in two sites and that subsequent piece if flipped and reinserted. In haemophilia B ,Mutations in the F9 gene are the reason for the disease. More than 900 alterations in this gene have been identified and thhe most common mutations change single DNA building blocks (base pairs) in the gene. The location for this is the F9 gene is located on the long (q) arm of the X chromosome between positions 27.1 and 27.2. Males have only one X, so there is no masking of the defective gene by another X; this basically guarantees that the defective gene will present itself in any male who has a defective X. Females have a low chance of expression as a female having two defective copies of the gene is very low, thus females are almost always non symptomatic carriers of hemophilia. Females carriers can only inherit the defective gene from either their mother, father, or it some cases it could be a autosomal mutation. Only under rare circumstances do females actually have haemophilia.

The Y-chromosome in men has no gene for factors VIII or IX. If the genes responsible for production of factor VIII or factor IX present on a male's X-chromosome are deficient there is no equivalent on the Y-chromosome, so the deficient gene is not masked by the dominant allele and he will develop the illness.A male receives only a single X-chromosome from his mother so a son of a healthy female may be at risk if the female is carrying a deficient gene. Haemophiliac daughters are more common than they once were, as improved treatments for the disease have allowed more haemophiliac males to survive to adulthood and become parents.

A mother who is a carrier has a 50% chance of passing the faulty X chromosome to her daughter, while an affected father will always pass on the affected gene to his daughters. A son cannot inherit the defective gene from his father.

As with all genetic disorders, it is of course also possible for a human to acquire it spontaneously through mutation, rather than inheriting it, because of a new mutation in one of their parents' gametes. Spontaneous mutations account for about 33% of all cases of haemophilia A. About 30% of cases of haemophilia B are the result of a spontaneous gene mutation.

With the severe problems that arise with Haemophilia, numerous doctors are currently working to find a cure to treat this disease. One research study that may help to understand and find a cure dealt with Inhibitors in mild/moderate haemophilia A. Haemophilia A is caused by a deficiency of factor (F) VIII. Therapy is based on the replacement of FVIII to haemostatically adequate levels for the prevention or treatment of bleeds. Inhibitors neutralizing the haemostatic effects of FVIII have been recognized as a complication of haemophilia since the introduction of replacement therapy. In MMHA, they occur later in life than in severe haemophilia and are generally associated with a change in bleeding pattern. Many of these patients experience severe spontaneous bleeding in joints and muscles Two cases were studied , patient 1 and patient 2. In the first , the patient was given drugs that prevented the formation of inhibitors and allowed the factor to prevail. In patient 2 , the patient received a different treatment and still getting that treatment ot prevent inhibitors from forming. In the second the patient did not get the same type of treatment and thus still suffered from bleeding. A range of therapeutic options to eradicate the inhibitor is currently available and a variety of treatments can also be used to treat the bleeding episodes. However, the optimal treatment regimen for the eradication of inhibitors in MMHA and for the treatment of bleeding episodes have yet to be established.