Medical Topic Research Blog

Topic: Hemophilia by Shannon Lee

Definitions and Analysis (Word Parts) of Five Medical Terms

A. Word analysis for immunologic

immun/o (CF) = safe, immunity

log (R) = study

-ic (S) = pertaining to

Meaning: Pertains to the study of immunity

B. Word analysis for monoclonal

mono- (P) = one

clon/o (CF) = turmoil

-al (S) = pertaining to

Meaning: Pertains to one turmoil

C. Word analysis for polyangiitis

poly- (P) = many, much, excessive

angi (R) = vessel

-itis (S) = inflammation

Meaning: The inflammation of many vessels.

D. Word analysis for prophylactic

pro- (P) = before, in front of

phylact- (P) = guard, protect, preserve

-ic (S) = pertaining to

Meaning: Pertains to before, or preventing a disease

E. Word analysis for thrombocytopenia

thromb/o (CF) = clot

cyt/o (CF) = cell

-penia (S) = lack of, deficiency, abnormal reduction

Meaning: The lack of a clot in cells.

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Hemophilia is a group of hereditary genetic disorders that impairs the body's ability to control blood clotting, which is used to stop bleeding when a blood vessel is broken (Liu, 2015). Hemophilia A is the most common form of the disorder, present in about 1 in 5,000 - 10,000 male births. Hemophilia B occurs in around 1 in about 20,000 - 34,000 male births (Iorio, 2011). Like other recessive sex-linked, X chromosome disorders, hemophilia is more likely to occur in males than that of females. This is because females have two X chromosomes while males have only one, so they defective gene is guaranteed to manifest in any male who carries it (Athale, 2015). Because females have two X chromosomes and hemophilia is a rare disorder, the chances of a female having two defective copies of the gene is very remote, so females are almost exclusively asymptomatic carriers of this disorder. Female carriers can inherit the defective gene from either their mother or father, or it may be a new mutation. Although it is not impossible for a female to have hemophilia, it is unusual: daughters which are the product of both a male with hemophilia A or B and a female carrier will possess a 50% chance of having hemophilia (Athale, 2015).

People with hemophilia have lower clotting factor level of blood plasma or impaired activity of the coagulation factors needed for a normal clotting process (Iorio, 2011). Thus when a blood vessel is injured, a temporary scab does form, but the missing coagulation factors prevent fibrin formation, which is necessary to maintain the blood clot (Liu, 2015). A hemophiliac does not bleed more intensely than a person without it, but it can bleed for a much longer time. In severe hemophiliacs even a minor injury can result in blood loss lasting days or weeks, or even never healing completely. In areas such as the brain or inside joints, this can be fatal or permanently debilitating (Athale, 2015).

Hemophilia A

Hemophilia A is inherited as an X-linked recessive trait, and thus occurs in males and in homozygous females. However, mild hemophilia A is known to occur in heterozygous females due to X-inactivation, so it is recommended that levels of factor VIII and IX be measured in all known or potential carriers prior to surgery and in the event of clinically significant bleeding (Iorio, 2011). 5-10% of patients with hemophilia A are affected because they make a dysfunctional version of the factor VIII protein, while the remainder are affected because they produce factor VIII in insufficient amounts (Liu, 2015). Of those who have severe deficiency, 45-50% have the same mutation, an inversion within the factor VIII gene that results in total elimination of protein production (Liu, 2015).

Hemophilia B

Hemophilia B is a blood clotting disorder caused by a mutation of the factor IX gene, leading to a deficiency of factor IX. It is the second most common form of hemophilia next to hemophilia A. The factor IX gene is located on the X chromosome. In 1990, George Brownlee and Merlin Crossley showed that two sets of genetic mutations were preventing two key proteins from attaching to the DNA of people with a rare and unusual form of hemophilia B - hemophilia B Leyden - where sufferers experienced episodes of excessive bleeding in childhood, but have few bleeding problems after puberty. This lack of protein attachment to the DNA was thereby turning off the gene that produces clotting factor IX, which prevents excessive bleeding (Athale, 2015).