By Omogoroye Olumide
SICKLE CELL DISEASE
Sickle cell disease; a serious hereditary disease that affects the red blood cells. It is hereditary in the sense that it is being transferred from parents to offsprings.
Though, the disease is passed from parents to offsprings, the parents might not be suffering from the disease. This is because sickle cell disease is an autosomal recessive disease i.e it only occurs if both the father and mother have atleast a copy each of the defective gene that is responsible for the disease.
There are three possible inheritance scenario that can lead to a child having sickle cell disease:
1. Both parents having sickle cell trait i.e both parents have only one copy each of the defective gene.
2. One parent has sickle cell disease and the other has sickle cell trait i.e one of the parent has two copies of the defective gene while the other has one copy.
3. Both parents have sickle cell disease i.e both parents have two copies each of the defective gene.
Sickle cell disease is a genetic disorder where the body produces an abnormal hemoglobin called hemoglobin S. Hemoglobin is the protein in red blood cells that carries oxygen. Hemoglobin transports oxygen from the lungs to other parts of the body. Hemoglobin is made up of four different protein subunit, which includes two subunits called alpha-globin and two subunits called beta-globin.
Cause of sickle cell disease
Sickle cell disease is caused by a point mutation in the beta-globin chain of hemoglobin, causing the hydrophilic amino acid glutamic acid to be replaced with the hydrophobic amino acid valine at the sixth position.
The beta-globin gene is found on the short arm of chromosome 11. The association of two wild-type alpha-globin subunits with two mutant beta-globin subunits forms hemoglobin S (HbS). Under low-oxygen conditions (being at high altitude, for example), the absence of a polar amino acid at position six of the beta-globin chain promotes the non-covalent polymerisation (aggregation) of hemoglobin, which distorts red blood cells into a sickle shape and decreases their elasticity. Pardon the usage of complex words in this paragraph.
Red blood cells with normal hemoglobin (hemoglobin-A) have a biconcave shape ( flattened disc shape) to maximize their surface area for oxygen absorption.
In people with sickle cell disease, there is presence of red blood cells with abnormal hemoglobin molecules (hemoglobin-S) which have a sickle shape instead of the normal biconcave shape. Their shape causes the red blood cells to pile up, thereby blocking and damaging vital organs and tissues if the body.
These sickle shaped cells are destroyed in the bodies of people with the disease, causing anemia. This anemia is what gives the disease its commonly known name - sickle cell anemia.
Sickle cells also block the flow of blood through the blood vessels, resulting in lung tissue damage that causes acute chest syndrome, pain episodes, stroke and priapism (painful, prolonged erection). It also causes damage to the spleen, kidneys and liver. The damage to the spleen makes patients - especially young children - easily overwhelmed by bacterial infections. Patients suffering from this disease have crises upon crises and tend to be hospitalized often.
Symptoms of Sickle cell disease
1. Periods of pain that can last a few hours to a few days.
2. Blood clots.
3. Swelling in hands and feet.
4. Joint pain that resembles arthritis.
5. Chronic neuropathic pain (nerve pain).
6. Life-threatening infections.
7. Anemia (decrease in red blood cells).
8. Excessive fatigue or irritability, from anemia.
9. Fussiness, in babies.
10. Bedwetting, from associated kidney problems.
10. Jaundice, which is yellowing of the eyes and skin etc.
Some complications of sickle cell disease
Sickle cell disease can cause severe complications which appear when the sickle cells block vessels in different parts of the body. Painful or damaging blockages are called sickle cell crises.
Listed below are some of the complications that can result from sickle cell disease:
1. Delayed growth.
2. Skin ulcers.
3. Neurological complications.
4. Severe anemia.
5. Hand-foot syndrome.
6. Eye problems.
7. Heart disease and chest syndrome.
8. Lung disease.
9. Priapism.
10. Gall stone.
11. Splenic sequestration etc.
How is the disease diagnosed?
Doctors diagnose sickle cell through a blood test that checks for hemoglobin S - the defective form of hemoglobin. To confirm the diagnosis, a sample of blood is examined under a microscope to check for large numbers of sickled red blood cells - the hallmark trait of the disease.
Sickle cell disease can also be detected in an unborn baby. Amniocentesis, a procedure in which a needle is used to take fluid from around the baby for testing, can show whether the fetus has sickle cell disease or carries the sickle cell gene. If the test shows that the child will have sickle cell disease, some parents may choose not to continue the pregnancy. Genetic counselors can help parents make these difficult decisions.
Treatments and cure of sickle cell disease
Until recently, people with sickle cell disease were not expected to survive childhood. But today, due to preventive drug treatment, improved medical care and aggressive research, half of sickle cell patients live beyond 50 years.
Treatments for sickle cell include antibiotics, pain management and blood transfusions. A new drug treatment, hydroxyurea, which is an anti-tumor drug, appears to stimulate the production of fetal hemoglobin, a type of hemoglobin usually found only in newborns. Fetal hemoglobin helps prevent the "sickling" of red blood cells. Patients treated with hydroxyurea also have fewer attacks of acute chest syndrome and need fewer blood transfusions.
Bone Marrow Transplantation: The Only Cure:
Currently the only cure for sickle cell disease is bone marrow transplantation. In this procedure a sick patient is transplanted with bone marrow from healthy, genetically compatible sibling donors. However only about 18 percent of children with sickle cell disease have a healthy, matched sibling donor. Bone marrow transplantation is a risky procedure with many complications.
Gene Therapy Offers Promise of a Cure:
Researchers are experimenting with attempts to cure sickle cell disease by correcting the defective gene and inserting it into the bone marrow of those with sickle cell to stimulate production of normal hemoglobin. Recent experiments show promise.
Researchers used bioengineering to create mice with a human gene that produces the defective hemoglobin causing sickle cell disease. Bone marrow containing the defective hemoglobin gene was removed from the mice and genetically "corrected" by the addition of the anti-sickling human beta-hemoglobin gene. The corrected marrow was then transplanted into other mice with sickle cell disease. The genetically corrected mice began producing high levels of normal red blood cells and showed a dramatic reduction in sickled cells. Scientists are hopeful that the techniques can be applied to human gene transplantation using autologous transplantation, in which some of the patient's own bone marrow cells would be removed and genetically corrected.
How do I know if I have the disease?
If you have some of the symptoms listed above, it's possible you have the disease. But to be sure, visit a medical laboratory to conduct a blood test to determine your genotype. Your genotype will show whether you have a copy of the gene responsible for the disease. It also shows the number of the gene present in you.
The three common genotypes are: AA, AS, SS. AA shows that there is no copy of the defective gene present. People with this genotype can't suffer from the disease and can't transfer it to their offspring. AS shows a single copy of the defective gene is present. People with this genotype also won't suffer from the disease but they are a carrier of the trait, hence, they can transfer it to their offspring. SS shows that there is two copies of the defective gene present and there is no copy of the normal gene. People with this genotype suffers from the disease and also pass the trait to their offspring. So after seeing the result you will know the category you belong to.
I will advise you know your genotype and blood group as they are very essential. And also before going into a relationship (marriage) seek the advice of a genetic counsellor inorder to save your marriage and offsprings.
Thanks for taking your time to read this, I know you have gotten one thing or the other. Please help share this post with people, you will be increasing the awareness of sickle cell disease by doing so. Thank you once again.
SICKLE CELL DISEASE
Sickle cell disease; a serious hereditary disease that affects the red blood cells. It is hereditary in the sense that it is being transferred from parents to offsprings.
Though, the disease is passed from parents to offsprings, the parents might not be suffering from the disease. This is because sickle cell disease is an autosomal recessive disease i.e it only occurs if both the father and mother have atleast a copy each of the defective gene that is responsible for the disease.
There are three possible inheritance scenario that can lead to a child having sickle cell disease:
1. Both parents having sickle cell trait i.e both parents have only one copy each of the defective gene.
2. One parent has sickle cell disease and the other has sickle cell trait i.e one of the parent has two copies of the defective gene while the other has one copy.
3. Both parents have sickle cell disease i.e both parents have two copies each of the defective gene.
Sickle cell disease is a genetic disorder where the body produces an abnormal hemoglobin called hemoglobin S. Hemoglobin is the protein in red blood cells that carries oxygen. Hemoglobin transports oxygen from the lungs to other parts of the body. Hemoglobin is made up of four different protein subunit, which includes two subunits called alpha-globin and two subunits called beta-globin.
Cause of sickle cell disease
Sickle cell disease is caused by a point mutation in the beta-globin chain of hemoglobin, causing the hydrophilic amino acid glutamic acid to be replaced with the hydrophobic amino acid valine at the sixth position.
The beta-globin gene is found on the short arm of chromosome 11. The association of two wild-type alpha-globin subunits with two mutant beta-globin subunits forms hemoglobin S (HbS). Under low-oxygen conditions (being at high altitude, for example), the absence of a polar amino acid at position six of the beta-globin chain promotes the non-covalent polymerisation (aggregation) of hemoglobin, which distorts red blood cells into a sickle shape and decreases their elasticity. Pardon the usage of complex words in this paragraph.
Red blood cells with normal hemoglobin (hemoglobin-A) have a biconcave shape ( flattened disc shape) to maximize their surface area for oxygen absorption.
In people with sickle cell disease, there is presence of red blood cells with abnormal hemoglobin molecules (hemoglobin-S) which have a sickle shape instead of the normal biconcave shape. Their shape causes the red blood cells to pile up, thereby blocking and damaging vital organs and tissues if the body.
These sickle shaped cells are destroyed in the bodies of people with the disease, causing anemia. This anemia is what gives the disease its commonly known name - sickle cell anemia.
Sickle cells also block the flow of blood through the blood vessels, resulting in lung tissue damage that causes acute chest syndrome, pain episodes, stroke and priapism (painful, prolonged erection). It also causes damage to the spleen, kidneys and liver. The damage to the spleen makes patients - especially young children - easily overwhelmed by bacterial infections. Patients suffering from this disease have crises upon crises and tend to be hospitalized often.
Symptoms of Sickle cell disease
1. Periods of pain that can last a few hours to a few days.
2. Blood clots.
3. Swelling in hands and feet.
4. Joint pain that resembles arthritis.
5. Chronic neuropathic pain (nerve pain).
6. Life-threatening infections.
7. Anemia (decrease in red blood cells).
8. Excessive fatigue or irritability, from anemia.
9. Fussiness, in babies.
10. Bedwetting, from associated kidney problems.
10. Jaundice, which is yellowing of the eyes and skin etc.
Some complications of sickle cell disease
Sickle cell disease can cause severe complications which appear when the sickle cells block vessels in different parts of the body. Painful or damaging blockages are called sickle cell crises.
Listed below are some of the complications that can result from sickle cell disease:
1. Delayed growth.
2. Skin ulcers.
3. Neurological complications.
4. Severe anemia.
5. Hand-foot syndrome.
6. Eye problems.
7. Heart disease and chest syndrome.
8. Lung disease.
9. Priapism.
10. Gall stone.
11. Splenic sequestration etc.
How is the disease diagnosed?
Doctors diagnose sickle cell through a blood test that checks for hemoglobin S - the defective form of hemoglobin. To confirm the diagnosis, a sample of blood is examined under a microscope to check for large numbers of sickled red blood cells - the hallmark trait of the disease.
Sickle cell disease can also be detected in an unborn baby. Amniocentesis, a procedure in which a needle is used to take fluid from around the baby for testing, can show whether the fetus has sickle cell disease or carries the sickle cell gene. If the test shows that the child will have sickle cell disease, some parents may choose not to continue the pregnancy. Genetic counselors can help parents make these difficult decisions.
Treatments and cure of sickle cell disease
Until recently, people with sickle cell disease were not expected to survive childhood. But today, due to preventive drug treatment, improved medical care and aggressive research, half of sickle cell patients live beyond 50 years.
Treatments for sickle cell include antibiotics, pain management and blood transfusions. A new drug treatment, hydroxyurea, which is an anti-tumor drug, appears to stimulate the production of fetal hemoglobin, a type of hemoglobin usually found only in newborns. Fetal hemoglobin helps prevent the "sickling" of red blood cells. Patients treated with hydroxyurea also have fewer attacks of acute chest syndrome and need fewer blood transfusions.
Bone Marrow Transplantation: The Only Cure:
Currently the only cure for sickle cell disease is bone marrow transplantation. In this procedure a sick patient is transplanted with bone marrow from healthy, genetically compatible sibling donors. However only about 18 percent of children with sickle cell disease have a healthy, matched sibling donor. Bone marrow transplantation is a risky procedure with many complications.
Gene Therapy Offers Promise of a Cure:
Researchers are experimenting with attempts to cure sickle cell disease by correcting the defective gene and inserting it into the bone marrow of those with sickle cell to stimulate production of normal hemoglobin. Recent experiments show promise.
Researchers used bioengineering to create mice with a human gene that produces the defective hemoglobin causing sickle cell disease. Bone marrow containing the defective hemoglobin gene was removed from the mice and genetically "corrected" by the addition of the anti-sickling human beta-hemoglobin gene. The corrected marrow was then transplanted into other mice with sickle cell disease. The genetically corrected mice began producing high levels of normal red blood cells and showed a dramatic reduction in sickled cells. Scientists are hopeful that the techniques can be applied to human gene transplantation using autologous transplantation, in which some of the patient's own bone marrow cells would be removed and genetically corrected.
How do I know if I have the disease?
If you have some of the symptoms listed above, it's possible you have the disease. But to be sure, visit a medical laboratory to conduct a blood test to determine your genotype. Your genotype will show whether you have a copy of the gene responsible for the disease. It also shows the number of the gene present in you.
The three common genotypes are: AA, AS, SS. AA shows that there is no copy of the defective gene present. People with this genotype can't suffer from the disease and can't transfer it to their offspring. AS shows a single copy of the defective gene is present. People with this genotype also won't suffer from the disease but they are a carrier of the trait, hence, they can transfer it to their offspring. SS shows that there is two copies of the defective gene present and there is no copy of the normal gene. People with this genotype suffers from the disease and also pass the trait to their offspring. So after seeing the result you will know the category you belong to.
I will advise you know your genotype and blood group as they are very essential. And also before going into a relationship (marriage) seek the advice of a genetic counsellor inorder to save your marriage and offsprings.
Thanks for taking your time to read this, I know you have gotten one thing or the other. Please help share this post with people, you will be increasing the awareness of sickle cell disease by doing so. Thank you once again.
I have a relative with sickle cell disease. It's sad that the only way to treat her permanently is very expensive in this part of the world.
ReplyDeleteAbout gene therapy, the idea shows real promise. Hm.
Great write-up. 👍🏽
Sickle cell is one of the major challenges in the field of health and sciences and I think it should be spoke about more often. This makes this write up very important. I'm glad that it is self explanatory and full of content. Thank you!
ReplyDeleteYou doing well
ReplyDelete