Sickle Cell Anemia
Updated on May 25th, 2019
Over 100,000 people in the United States have sickle cell anemia, a disease that can cause multiple complications and lead to a shorter lifespan. At YourDNA, we want you to have the information you need to know to manage your condition at your fingertips.
Sickle Cell Anemia is a disease that is most common among African Americans. Approximately 1 in 13 African American babies is born with the sickle cell trait.
Approximately 1 in every 365 black children are born with sickle cell anemia. However, it can also affect Hispanics, South Asians, caucasians from Southern Europe and individuals from the Middle East.
According to the National Institutes of Health, approximately 100,000 people in the United States and 20 million people worldwide have sickle cell disease, which causes a mutation in the red blood cell. This mutation causes blockage of blood flow due to the sickling shape and a constant shortage of red blood cells.
The median life expectancy for an individual with sickle cell anemia is between 42 and 48 years.
How is Sickle Cell Anemia Inherited?
Sickle cell anemia is inherited from a defect in a person’s gene, and those with the disease are diagnosed at birth.
A sickle cell carrier is someone who has the recessive sickle cell trait. In order for an individual have sickle cell anemia, they must inherit two sickle cell trait genes. One trait gene comes from each parent.
Those who have the sickle cell trait are usually healthy. They live normal lives and rarely have any complications. However, they are able to pass this trait down to their children.
The children, in turn, either inherit the trait which makes them a carrier, or develop the painful sickle cell anemia.
What Causes Sickle Cell Anemia?
Sickle cell anemia is caused by a mutation in hemoglobin. Hemoglobin helps to carry oxygen throughout the body.
Normally, red blood cells are round in shape, making it easy for them to transport oxygen. With sickle cell anemia, the hemoglobin turns into stiff rods inside of the red blood cells.
These stiff rods then cause the shape of the red blood cells to change. So, instead of red blood cells being their normal round, disc shape, they turn into a crescent or sickle shape.
Cresent or sickle-shaped cells are not flexible. This means that they cannot change shape easily in order to squeeze through the blood vessels.
This means that the blood gets thick and cannot travel through the body as well. Sickle cells also die a lot quicker than normal red blood cells, surviving only for 10 to 20 days, compared to the 90 to 120 days that normal red blood cells live.
Since these cells die so quickly, it’s hard for the body to keep up and make enough new cells to replace the dead ones. This leads to a decrease in red blood cells, known as anemia.
What Are the Complications of Sickle Cell Anemia?
The main issue with sickle cell anemia is that the abnormal-shaped red blood cells block the entry of healthy red blood cells through the body.
This prevents oxygen from reaching various tissues and organs. There are other potential complications, too, that require treatment and care.
The first complication is anemia due to the early death of red blood cells. Anemia means that there is an inadequate amount of red blood cells in the body to carry oxygen. Anemic patients may experience a variety of symptoms including:
- Difficulty breathing
- Pale skin
- Tachycardia (fast heart rate)
- Slow growth and delayed puberty
This is a very typical complication of sickle cell anemia. Prevention includes regular screening and watching for the signs of anemia along with blood transfusions.
Pain crisis is the most common complication of sickle cell anemia. It is also the number one reason that individuals with sickle cell anemia go to the hospital or emergency room.
When the mutated cells get clogged in blood vessels and block the blood flow, it can cause pain that can last for days and be very severe. Prevention includes ensuring adequate hydration, monitoring temperatures, limit exposure to high altitudes and taking hydroxyurea.
Infection is the leading cause of death within sickle cell patients. Since sickled cells often block the blood vessels in organs, it can cause damage to the spleen.
The spleen is the organ responsible for filtering bacteria out of the bloodstream and producing antibodies. When the spleen does not work properly, the immune system is impaired and it leaves sickle cell anemia patients at higher risk for infections.
Prevention of infections includes regular vaccinations, good hand hygiene, careful preparation of food and prophylactic antibiotics.
When the blood vessels in the spleen get clogged, it can also cause the spleen to enlarge. When the spleen enlarges, this is called splenic sequestration, which can be a life-threatening complication of sickle cell anemia. Symptoms include:
- Sudden weakness
- Pale lips
- Tachypnea (fast breathing)
- Abdominal pain on the left side of the body
- Extreme thirst
- Fast heartbeat
Prevention of this complication includes regular blood transfusions and/or removal of the spleen (splenectomy).
Loss of Vision
Another complication of sickle cell anemia is vision loss. When the blood vessels leading to the eye get clogged by sickled cells, it can restrict blood flow to the eye and damage the retina.
Prevention of this includes yearly eye exams to assess for damage to the retina.
Strokes can happen when sickled cells get clogged in a blood vessel and block the blood flow to the brain. Approximately 10 percent of children with sickle cell anemia will have a stroke.
Strokes can easily cause damage to the brain, learning issues, and other lifelong disabilities. Stroke prevention in sickle cell patients requires frequent transcranial doppler ultrasounds.
If patients have abnormal transcranial doppler ultrasounds, doctors may recommend chronic blood transfusions to help aid in the prevention of a stroke.
Deep Vein Thrombosis
Another very serious complication of sickle cell anemia is the development of a deep vein thrombosis or pulmonary embolism. This is a blood clot within the deep veins which can lead to disability and even death.
Prevention includes close monitoring and taking medications such as heparin or warfarin, which thin out the blood and make it flow easier.
Acute Chest Syndrome
Lastly, one of the most serious and life-threatening complications that can happen to patients with sickle cell anemia is acute chest syndrome. Patients with acute chest syndrome with present with chest pain, coughing, difficulty breathing and a fever.
Prevention is hydroxyurea and use of incentive spirometer for those who are on bed rest.
Diagnosis of Sickle Cell Anemia
How Do You Diagnose Sickle Cell Anemia?
Sickle cell anemia is usually diagnosed by a blood sample taken from the heel or finger of a baby. This is part of the routine blood testing that is done on newborns in the United States.
It can also be diagnosed through a blood test in adults taken from a vein in the arm.
The sample is sent to a laboratory to test for hemoglobin S. Hemoglobin S is the defected version of hemoglobin which causes sickle cell anemia. A negative test means that the patient does not have sickle cell anemia.
A positive test means that the patient has a sickle cell gene. Further testing will be needed to determine whether the patient has one or two sickle cell genes.
Two sickle cell genes means that the patient has sickle cell anemia. One sickle cell gene means that the patient is only a carrier of the sickle cell trait.
Some physicians may deem it necessary to get a complete blood count which will show whether or not the patient has anemia or a low red blood cell count, which is a complication of the disease. Hemoglobin electrophoresis, high performance liquid chromatography (HPLC), or DNA testing can be used to figure out what type of hemoglobin is present in the blood.
Hemoglobin electrophoresis is a blood test that detects the type of hemoglobin a person has in their blood. This will help doctors determine whether their disease is sickle cell related or not.
High performance liquid chromatography can also be done to differentiate and determine what type of hemoglobin a person has.
Can This Be Detected Before Birth?
It’s possible to check for sickle cell anemia before a child is born. Many families with two parents who have the sickle cell trait may want to find out sooner rather than later if their child will inherit the sickle cell anemia disease.
Genetic counselors can help at-risk families decide if checking before birth is necessary. Sickle cell anemia can be diagnosed in a fetus through amniocentesis, by a inserting a needle into the abdomen to retrieve a sample of the amniotic fluid.
The sample is then sent to a lab where it will be checked for the disease.
Sickle Cell Anemia Genetics
There are four different genetic outcomes for patients.
- The first outcome is a normal patient. This patient will inherit two sets of genes, one set from each parent. They will inherit two sets of normal hemoglobin otherwise known as hemoglobin A. This means that they will have normal shape and function of their red blood cells. In this outcome, neither of their parents have any abnormal sickle cell trait or disease.
- The second outcome is when a person inherits one set of normal hemoglobin A genes and one set of an abnormal or hemoglobin S gene. These individuals are carriers of the sickle cell trait. These patients typically have a majority of normal cells but under unlikely extreme conditions, their cells can become sickled. One of their parents is likely to be a carrier of the sickle cell trait while the other is not.
- The third outcome is when a person inherits two sets of the abnormal hemoglobin S gene. These individuals have sickle cell anemia. Both of their parents either have the sickle cell trait or have the disease. These sickled red blood cells cause many painful sickle cell crises.
- The fourth outcome is when the individual inherits one set of genes with abnormal hemoglobin S and one set of genes with another type of abnormal hemoglobin. Although they may not have the exact same type of sickle cell anemia, these patients can be plagued with mild or even severe sickle cell complications. This means that both of their parents had abnormal hemoglobin traits or disease, and passed it down to their children.
Genetic Tests for Sickle Cell Anemia
Genetic testing is available for sickle cell anemia. They are done to assess the DNA of a person’s cells.
The test can detect changes in a person’s genes, or it can check the number, order, and structure of a person’s chromosomes. Testing may be done on various types of samples, including body tissue, blood, or other body fluids such as urine or saliva.
Where Can I Go For a Genetic Test for my Child?
If you’re interested in getting genetic testing done, it’s recommended that you discuss options with your pediatrician or primary care physician. There are many places you can get genetic testing, however, your pediatrician will know the best places near you to go if they do not offer it themselves.
How is Sickle Cell Anemia Inherited?
Sickle cell anemia is passed down from their parent’s genes during pregnancy. Each parent will pass down specific genes that affect hemoglobin.
Depending on what they pass down, their child may develop sickle cell anemia. It’s not possible to develop sickle cell anemia after birth.
Either a person has it when they are born, or they don’t. However, if they don’t have symptoms early in life and their parents are unaware of their sickle cell trait status, it can go undetected until further complications arise.
What Are the Chances That I Will Pass Sickle Cell Anemia Onto my Child?
Since sickle cell anemia is a recessive disorder, both parents of a child must have the sickle cell trait in order to pass sickle cell down to their child. If one parent has the sickle cell trait, the child will not have sickle cell anemia, however, there’s a 1-in-4 (or 25 percent) chance of inheriting the sickle cell trait.
If both parents have the sickle cell trait there is a 50 percent chance that any of their children will also have the sickle cell trait. This, however, only includes children who only inherit the sickle cell gene from one parent.
These children do not have any symptoms of the disease, however they can pass their sickle cell trait on to their children.
If both parents have the sickle cell trait, there is a 25 percent or 1-in-4 chance that any of their children will inherit sickle cell anemia.
It’s important to get genetic counseling before having a child. Education and understanding the risk is important for families with a history of sickle cell anemia to know.
If I Have one Child With Sickle Cell Anemia Will all my Children Have it?
Having one child with sickle cell anemia does not necessarily mean that all of your children will have it. However, this does not mean that it is not possible for all of your children to have it either.
If both you and your partner have sickle cell anemia and are planning to have children, it’s important to understand that each child that you have has a 25 percent chance of developing sickle cell anemia. This also means that each child that you have has a 75 percent chance of not having sickle cell anemia.
Who Does Sickle Cell Anemia Typically Affect?
Sickle cell anemia typically affects African Americans of both genders.
However, it is possible for sickle cell anemia to affect Hispanics, South Asians, caucasians from Southern Europe and individuals from the Middle East. Sickle cell anemia is thought to have started in Africa, and it’s a lifelong disease.
Sickle Cell Anemia Treatment Options
Generally, sickle cell anemia is very limited to symptom management. Treatment options include childhood vaccinations, antibiotics, pain management, blood transfusions and hydroxyurea.
For patients with sickle cell anemia, it’s vital for them to be up to date with their vaccinations. These vaccines will help to prevent deadly infections.
Pneumonia is a leading cause of death in young children and infants with sickle cell anemia. It’s important for families to take precautions such as good hand hygiene, get the flu vaccine every year as well as the pneumococcal vaccine.
Patients with sickle cell anemia have a higher risk of developing a pneumococcal disease. For this reason, antibiotics are often prescribed to patients with sickle cell as a prophylactic treatment.
This means it is used to prevent any pneumococcal infection before it happens. Many sickle cell patients have the option to be on lifelong prophylactic antibiotic treatment.
However, it’s important for children to take penicillin or other antibiotics every day until they are at least 5 years of age at least.
Pain management within the sickle cell anemia community is usually very aggressive. It includes hospitalization, the use of anti-inflammatory medications such as ketorolac, blood transfusions, intravenous rehydration therapy, stool softeners, and narcotics such as hydromorphone and much more.
Typically, this type of aggressive treatment is only necessary when a patient has a sickle cell crisis (or acute pain caused by the sickling of their blood).
Blood transfusions are very useful and frequent with patients who have sickle cell anemia. Patients with the disease have the option to get blood transfusions regularly, sometimes as often as every month, to prevent sickle cell crises from occurring.
During blood transfusions, patients receive blood from a matched donor to replace the blood cells in their body that are sickled and causing pain crisis. When blood becomes sickled, it can clump together and block blood vessels, making it hard for vital organs such as the heart and spleen.
Chronic transfusions of healthy red blood cells can decrease the number of complications related to sickle cell anemia.
Hydroxyurea, an anti-tumor drug, is a new treatment option that has been used in sickle cell patients. It stimulates the production of fetal hemoglobin which is generally only found in newborns.
This type of hemoglobin helps to prevent red blood cells from sickling and it has been proven that patients who take this drug have fewer sickle cell crises attacks, fewer attacks of acute chest syndrome and need fewer blood transfusions. Many sickle cell patients prefer taking hydroxyurea daily instead of having regular blood transfusions.
Bone Marrow Transplants
The last way to treat sickle cell anemia is through bone marrow transplants, which is the only cure for sickle cell anemia. During this transplant, a sickle cell patient will receive bone marrow from a healthy, genetically compatible sibling donor.
Unfortunately, only about 18 percent of sickle cell anemia patients have compatible sibling donors.
Although this is an innovative procedure, it comes with many risks and complications. Due to the risks and limited availability of this procedure, it’s only performed in very severe cases of sickle cell anemia where they have organ damage, stroke or frequent pain crises.
The Prognosis for Sickle-Cell Anemia
Until recently, most individuals with sickle cell anemia were not expected to survive past childhood.
However, today due to improved research, medical care, and treatment options, half of the patients live beyond 50 years of age.
Does Sickle-Cell Anemia Go Away?
Sickle cell anemia is a lifelong disease. Since the only cure is by bone marrow transplant which is risky and limited in availability, most patients should expect to have this disease for the rest of their life. Thankfully for new research, most people with the disease are able to live long and fulfilling lives.