Causes
Although it is passed down from parents to children, about 1/3 of cases found have no previous family history. According to the US Centers for Disease Control and Prevention (CDC), hemophilia occurs in approximately 1 in 5,617 live male births. There are between 30,000 – 33,000 males with hemophilia in the US*.
Symptoms
Diagnosis. In the United States, most people with hemophilia are diagnosed at a very young age. 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. In about two thirds of cases, there is a family history of hemophilia.
Complications
In about two thirds of cases, there is a family history of hemophilia. The diagnosis of hemophilia is made using a special blood test and most babies can be tested soon after birth. Sometimes prenatal genetic testing is done to diagnose hemophilia before birth.
How common is hemophilia in males?
People with hemophilia have risk factors that have been associated with acute and chronic renal disease, such as HIV infection and kidney bleeding.
How old do you have to be to have hemophilia?
Does hemophilia run in families?
What are the risk factors for hemophilia?
Which gender gets hemophilia A more?
Hemophilia is caused by a mutation or change in the gene that regulates the production of factor VIII, an essential blood-clotting protein. Located on the X chromosome, hemophilia almost always occurs in males who only have one X chromosome.
Why are males much more likely to have hemophilia?
This means that males only have one copy of most of the genes on the X chromosome, whereas females have 2 copies. Thus, males can have a disease like hemophilia if they inherit an affected X chromosome that has a mutation in either the factor VIII or factor IX gene.
Are males more likely to have hemophilia?
Since males have only a single copy of any gene located on the X chromosome, they cannot offset damage to that gene with an additional copy as can females. Consequently, X-linked disorders such as Hemophilia A are far more common in males.
Why do females rarely get hemophilia?
Hemophilia is a rare blood disease that usually occurs in males. In fact, it's extremely rare for women to be born with the condition because of the way it's passed down genetically. A female would need to inherit two copies of the faulty gene — one from each parent — to develop hemophilia A, B or C.
Why is it rare for females to have hemophilia?
These disorders affect males more often than females because females have an additional X chromosome that acts as a “back-up.” Because males only have one X chromosome, any mutation in the factor VIII or IX gene will result in hemophilia.
What race is hemophilia most common in?
Prevalence was higher among whites (15.1) than blacks (12.4) or Hispanics of either race (12.4). State-specific prevalence varied from 1.6 to 23.3 cases per 100 000. Based on 9587 males born during the index period, the average haemophilia incidence was 1 case per 4334 live male births.
What age group is affected by hemophilia?
In the United States, most people with hemophilia are diagnosed at a very young age. 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.
How is hemophilia passed down?
Hemophilia A and hemophilia B are inherited in an X-linked recessive pattern . The genes associated with these conditions are located on the X chromosome, which is one of the two sex chromosomes . In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition.
Why is hemophilia more common in males than in females quizlet?
Why is hemophilia more common in males than in females? The gene for hemophilia is on the X chromosomes. Boys are XX and girls are XY so boys have twice as much chance at having hemophilia than girls.
Why is hemophilia more prevalent in males quizlet?
Why is hemophilia more prevalent in males? The defective gene is on the X chromosome; females have two copies, males only one hence the disease is more prevalent in males.
Where is hemophilia most prevalent?
Hemophilia prevalence varies widely across the United States and is highest in Midwestern and Northeastern states. The estimated incidence of hemophilia among U.S. births is 1 birth per 5,617 male births for hemophilia A and 1 birth per 19,283 male births for hemophilia B. Among all males with hemophilia, just over 4 in 10 have the severe form ...
Why is there a large variation in the prevalence of hemophilia between states?
A number of observations from this study need further investigation: The large variation in the prevalence of hemophilia between states is thought to be due primarily to the hereditary (passed down from one’s parents) nature of hemophilia and known migratory patterns (when people with hemophilia moved between states) early in U.S. history.
Why does hemophilia not clot?
Hemophilia is an inherited bleeding disorder in which the blood does not clot properly due to a lack or decrease in a protein called clotting factor. The two most common types of hemophilia are hemophilia A, which is due to a lack of clotting factor VIII (8) ...
What are the two most common types of hemophilia?
The two most common types of hemophilia are hemophilia A , which is due to a lack of clotting factor VIII (8) and hemophilia B, which is due to a lack of clotting factor IX (9). Either type can lead to spontaneous bleeding into muscles, organs, and joints as well as prolonged bleeding following injuries or surgery.
Why is hemophilia decreasing among black people?
The reason for the decreased prevalence of hemophilia among people of black race is not known.
How old are people with hemophilia?
Among all males with hemophilia, just over 4 in 10 have the severe form of the disorder. The average age of persons with hemophilia in the United States is 23.5 years. Compared to the distribution of race and ethnicity in the U.S. population, white race is more common, Hispanic ethnicity is equally common, while black race ...
What is the difference between prevalence and incidence?
Prevalence is a statistical concept referring to the number of cases of a disease that are present in a particular population at a given time, whereas incidence refers to the number of new cases that develop in a given period of time. .
Can females have hemophilia?
This is because these types of hemophilia result from a recessive mutation on the X chromosome. Females often have at least one healthy X chromosome, which means they will likely only become a carrier unless both parents pass on a recessive X chromosome.
Can hemophilia go away?
Though treatment can help improve and prevent symptoms, there is currently no cure for hemophilia. You will need regular treatment to ensure your blood clots normally.
What is a clotting factor?
Hemophilia is an inherited bleeding disorder in which a person lacks or has low levels of certain proteins called “clotting factors” and the blood doesn’t clot properly as a result. This leads to excessive bleeding. There are 13 types of clotting factors, and these work with platelets to help the blood clot. Platelets are small blood cells that ...
What is hemophilia C?
Hemophilia C is a mild form of the disease that’s caused by a deficiency of factor XI. People with this rare type of hemophilia often don’t experience spontaneous bleeding. Hemorrhaging typically occurs after trauma or surgery. Hemophilia is an inherited genetic condition.
How many types of clotting factors are there?
There are 13 types of clotting factors, and these work with platelets to help the blood clot. Platelets are small blood cells that form in your bone marrow. According to the World Federation of Hemophilia (WFH), about one in 10,000 people are born with this disease.
Why do females get X chromosomes?
Females receive an X chromosome from each parent. Because the genetic defect that causes hemophilia is located on the X chromosome, fathers can’t pass the disease to their sons. This also means that if a male gets the X chromosome with the altered gene from his mother, he’ll have hemophilia.
What are the three forms of hemophilia?
The three forms of hemophilia are hemophilia A, B, and C. Hemophilia A is the most common type of hemophilia, and it’s caused by a deficiency in factor VIII. According to the National Heart, Lung, and Blood Institute (NHLBI) Hemophilia B, which is also called Christmas disease, is caused by a deficiency of factor IX.
What does the clotting factor test measure?
This test measures how long it takes for blood to clot. It measures the clotting ability of factors VIII (8), IX (9), XI (11), and XII (12). If any of these clotting factors are too low, it takes longer than normal for the blood to clot. The results of this test will show a longer clotting time among people with hemophilia A or B.
What tests are done to check for hemophilia?
A doctor might check for hemophilia if a newborn is showing certain signs of hemophilia. Diagnosis includes screening tests and clotting factor tests. Screening tests are blood tests that show if the blood is clotting properly. Clotting factor tests, also called factor assays, are required to diagnose a bleeding disorder.
What is a screening test?
Screening tests are blood tests that show if the blood is clotting properly. Types of screening tests:
Why does bleeding go on for a long time?
Bleeding goes on for a long time after drawing blood and heel sticks (pricking the infant’s heel to draw blood for newborn screening tests). Bleeding in the head (scalp or brain) after a difficult delivery or after using special devices or instruments to help deliver the baby (e.g., vacuum or forceps).
When is hemophilia tested?
In the best of cases, testing for hemophilia is planned before the baby’s delivery so that a sample of blood can be drawn from the umbilical cord (which connects the mother and baby before birth) immediately after birth and tested to determine the level of the clotting factors.
Which is better, factor VIII or factor IX?
Umbilical cord blood testing is better at finding low levels of factor VIII (8) than it is at finding low levels of factor IX (9). This is because factor IX (9) levels take more time to develop and are not at a normal level until a baby is at least 6 months of age.
Can hemophilia cause bruises?
Unusual raised bruises or large numbers of bruises. If a child is not diagnosed with hemophilia during the newborn period, the family might notice unusual bruising once the child begins standing or crawling. Those with severe hemophilia can have serious bleeding problems right away.
What are the Symptoms of Hemophilia A?
People with hemophilia A bleed longer than other people. Bleeds can occur internally, into joints and muscles, or externally, from minor cuts, dental procedures, or injuries. How often a person bleeds and the severity of those bleeds depends on how much FVIII a person produces naturally.
How is Hemophilia A Treated?
Most treatments for hemophilia A focus on replacing the missing protein, FVIII (8), so a person can form a clot, and so reduce or eliminate the bleeds associated with the disorder. Treatments that work to prevent bleeding through new mechanisms have recently come to the market or are in clinical trials. People with hemophilia A have several different medication options for treatment.
What is the normal FVIII level?
Normal levels of FVIII range from 50% to 150%. Levels below 50% – or half of what is needed to form a clot – determine a person’s symptoms. • Mild hemophilia A: 6% up to 49% of FVIII in the blood. People with mild hemophilia A generally experience bleeding typically only after serious injury, trauma, or surgery.
How to prevent bleeds with hemophilia?
To maintain enough clotting factor in the bloodstream to prevent bleeds, patients with severe hemophilia are typically prescribed a regular treatment regimen, called prophylaxis – or prophy for short. This means a person will infuse their medication on a regular schedule – for example every day or every other day, depending on how long the factor lasts in the body. MASAC recommends prophylaxis as optimal therapy for all people with severe hemophilia A.
What is the genetic disorder of hemophilia?
What Is Hemophilia A? Hemophilia A, also called factor VIII (8) deficiency or classic hemophilia, is a genetic disorder caused by missing or defective factor VIII (FVIII), a clotting protein. Although it is passed down from parents to children, about 1/3 of cases found have no previous family history.
What is a daughter who inherits an X chromosome that contains the gene for hemophilia?
A daughter who inherits an X chromosome that contains the gene for hemophilia is called a carrier. She can pass the gene on to her children. Many women who carry the hemophilia gene also have low factor expression, which can result in heavy menstrual bleeding, easy bruising, and joint bleeds.
Why is it important to monitor for hemophilia?
If there is a known family history, it is important to monitor for symptoms. It is recommended that women who have a family history of hemophilia get tested before getting pregnant, to help prevent complications during childbirth.
What is Hemophilia?
Hemophilia is a genetic disorder that affects blood clotting. The two most common forms are hemophilia A and hemophilia B. Though the cause is different, the main effect is the same: people with hemophilia bleed for longer than normal.
How many alleles does hemophilia have?
Men with hemophilia have one non-working allele of either the F8 or F9 gene. Affected women usually have two non-working alleles of F8, or two non-working alleles of F9. It is rare, but carrier women who have one healthy allele and one non-working allele, can have mild symptoms.
What is the meaning of F9 in hemophilia?
People with hemophilia have only non-working alleles of either the F8 or the F9 genes meaning they are missing either coagulation factor VIII or IX protein. Some have less working protein than usual, and others have none at all. Either way, the coagulation factor signal chain is cut off or weakened. A blood clot cannot form. Without a blood clot, the injury is not sealed off and the person continues bleeding.
How does hemophilia affect genes?
Variation in genes other than F8 and F9 change the effects of hemophilia. For example, variations in genes influence blood vessel strength and elasticity. Strong, stetchy blood vessels are less likely to spontaneously tear and cause internal bleeding. Variations in genes that influence the number of platelets a person makes influence how well blood clots. Many gene variations influence the immune system. These variations affect how well hemophilia treatments work. Hemophilia is often treated with injection of healthy coagulation factor protein. Natural variation in immune system genes changes how well the body tolerates the injected protein.
When do hemophilia symptoms start?
The effects of hemophilia are different from person to person, both in severity and timing of symptoms. Often, symptoms first appear around the time a child learns to walk, as they start to get more bumps and bruises. Effects can first appear later in life as well, especially for mild forms.
When was the first treatment for hemophilia developed?
Hemophilia treatments have come a long way in terms of effectiveness and safety. The first treatment—direct blood trasfusion—was developed around 1840. However, even as recently as the 1950s, many people with hemophilia died in childhood. In the 1970s, people learned to concentrate coagulation factors from healthy blood donors. This treatment became safer when we learned to screen for and kill potential viruses (like HIV or hepatitis C) in donor blood. Now coagulation factor proteins can be made without donor blood, making them even safer.
Is hemophilia dangerous?
Untreated hemophilia is dangerous. It puts people at risk for spontaneous bleeding that is hard to stop. Bleeding may be internal, for example in the spaces around joints. Repeated bleeding episodes in joints can cause permanent damage.
What causes hemophilia?
Hemophilia is caused by a mutation (change) in one of the genes that provides instructions within cells for making clotting factor proteins in the blood. This mutation results in hemophilia by preventing the clotting factor protein from working properly or causing it to be missing altogether. These genes are located on the X chromosome. Males have one X and one Y chromosome (XY) and females have two X chromosomes (XX). A male inherits his X chromosome from his mother and his Y chromosome from his father. A females inherits one X chromosome from each parent. A male can have hemophilia if he inherits an affected X chromosome (an X chromosome with a mutation in the gene that causes hemophilia) from his mother.
How many chromosomes do males have?
Males have one X and one Y chromosome (XY) and females have two X chromosomes (XX). A male inherits his X chromosome from his mother and his Y chromosome from his father. A females inherits one X chromosome from each parent. A male can have hemophilia if he inherits an affected X chromosome ...
Why can't women have hemophilia?
Sometimes females with bleeding symptoms are not tested for hemophilia because there is often a misbelief that women can’t have hemophilia but can only be carriers. Thus, women with hemophilia might not get an accurate diagnosis. Although it is rarer for women to have hemophilia when compared to men, women can also have the condition.
Why is it important to raise awareness about hemophilia?
It is important to raise awareness about this fact to help women with hemophilia receive the care and support they need to live healthy lives. Below, Shellye, a woman living with hemophilia, shares her story about the challenges she has faced living with this condition.
Is a female a carrier of hemophilia?
When a female has one affected X chromosome, she is a “carrier” of hemophilia. Being a female carrier of hemophilia is not the same as having hemophilia, although female carriers may experience symptoms of hemophilia. A female carrier can also pass the affected X chromosome on to her children.
Can a female have hemophilia?
Females can also have hemophilia, but it is much rarer. When a female has hemophilia, both X chromosomes are affected or one is affected and the other is missing or non-functioning. In these females, bleeding symptoms can be similar to males with hemophilia.
About This Study
Main Findings from This Study
Critical Gaps & Future Directions
Paper Reference
Families with A History of Hemophilia
Families with No Previous History of Hemophilia
Screening Tests
Clotting Factor Tests