What is Sickle Cell Disease?
Sickle cell disease is a blood disorder that produces abnormally shaped red blood cells. It is not contagious. A person cannot catch it from someone else.
Sickle cell occurs when a child is born with two inherited sickle cell genes – one from each parent. If one normal hemoglobin gene and one sickle cell gene are inherited, a person will have the sickle cell trait. People with sickle cell trait do not have the disease; they are “carriers” with a 50/50 chance to pass the abnormal gene on to their children.
Healthy red blood cells are round, full of oxygen, and easily pass through the bodies’ smallest blood vessels.
Sickle cells are compromised and C-shaped, lacking normal oxygen levels. The sickled red blood cells stick and hook on each other, clumping together in small vessels clotting and stifling blood flow.
This can lead to pain crisis, acute chest syndrome, strokes, infections, and other complications. Over time, it leads to gradual destruction of organs and tissues throughout the body. SCD can harm a person’s spleen, brain, eyes, lungs, liver, heart, kidneys, penis, joints, bones, or skin.
The Process of Sickle Cell Disease
The symptoms and problems of sickle cell disease are a result of the abnormal hemoglobin S (HbS) molecule:
- When the sickle hemoglobin molecule loses its oxygen, it forms rigid rods called polymers that change the red blood cells into a sickle or crescent shape.
- These sickle-shaped cells stick to the walls and cannot squeeze through the capillaries. Blood flow through tiny blood vessels becomes slowed or stopped in many parts of the body. This deprives tissues and organs of oxygen. The higher the concentration of sickle hemoglobin and the more acidic the environment, the faster the sickle cell process is.
- When blood cells dry out (dehydrate), the density of hemoglobin S within the cell increases, thereby speeding the sickling process.
A NORMAL AND SICKLED RED BLOOD CELL
Normal Cell Sickled Cell
The Life of Red Blood Cells
Once matured, healthy red blood cells last for 90 to 120 days in the bloodstream, in comparison sickle disease red blood cells only last 10 to 20 days. Sickle cells can’t change shape easily, so they tend to burst apart or hemolyze.
Consequently, sickle cell patients cannot maintain sufficient red blood cell levels and are anemic as a result.This is one reason sickle cell disease is more commonly known as sickle cell anemia.
Sickle Cell Statistics
1.) Sickle cell anemia affects approximately 90,000 to 100,000 Americans.
2.) Sickle cell trait affects two million Americans.
3.) 1 in 365 African Americans and 1 in 16,300 Hispanics are born with SCD
4.) One in 12 African Americans is born with the sickle cell trait.
5.) There are millions of people with sickle cell disease worldwide.
How is Sickle Cell Disease Contracted?
Sickle cell is a genetic disease passed on from parents to their children. Each parent has two genes. Parents who have the sickle cell trait have a 50% chance to pass on a healthy gene and a 50% chance to pass on the sickle trait. Parents who have the disease always pass on a sickle cell trait gene to their children.
Example of a Four Child Family Inheritance Pattern
Each parent has the sickle cell trait:
One child born without any abnormalities
One child born with sickle cell disease
Two children born with the sickle cell trait
Each parent has sickle cell disease:
All four children would inherit the disease.
One Parent with the disease and one parent with the trait:
Two children will be born with the trait and two children with the disease
The different types of sickle disease result from the production of abnormal hemoglobin.
What is hemoglobin?
It is an essential component of red blood cells. Hemoglobin is a protein called heme found in red blood cells. It gives blood its red color and carries oxygen throughout the body. Sickle hemoglobin is not like normal hemoglobin. It can form stiff rods within the red cell, changing it into a crescent, or sickle shape.
The combination of different abnormal hemoglobin produces varying forms of the sickle cell disease.
Types Of Sickle Cell Disease
The most common forms of the disease are:
1.) HbSS – This “SS” form inherits two sickle cell genes, one “S” gene per parent. This is the most severe form of sickle cell.
2.) HbSC – This “SC” form inherits an “S” Gene from one parent and a hemoglobin “C” gene from the second parent. It can be a milder type of sickle cell disease.
3.) HbS beta thalassemia – “Sickle-beta-thal,” as its commonly known, is one “S” gene from one parent and one beta thalassemia gene from the other parent. Depending on the type of beta thalassemia inherited, the sickle disease can be mild or severe.
There are also rare forms of Sickle Cell Disease:
They are HbSD, HbSE, and HbSO
While these varying abnormal hemoglobin (C, beta thalassemia, etc) all pair with the “S” gene and form numerous versions of sickle cell anemia, they are all sickle cell disease. They all have red blood cells that sickle and compromise the oxygen-carrying capacity. They all cause clotting, cell hardening, anemia, and the hurt associated with pain crisis.
A Sickle Cell Cure?
Sickle Cell disease is curable by a transplant of stem cells or bone marrow.
Bone marrow is a soft, fatty tissue inside the center of the bones where blood cells are created. A bone marrow or stem cell transplant is a procedure that takes healthy blood-forming cells from one person, the donor, and puts them into someone with compromised bone marrow.
While they are cures, it is important to note, the Center for Disease Control describes the two procedures as “very risky” and can have serious side effects, including death. For the transplant to work, the donor bone marrow must be a close match to the recipient. Usually, the best donor is a sibling.
The Facts listed here were compiled and confirmed from the following websites – Center of Disease Control, Nation Institutes of Health’s National Heart, Lung and Blood Institute, The Mayo Clinic, and The Sickle Cell Disease Association of America