What is Sickle Cell Anaemia?
The disorder affects the red blood cells which contain a
special protein called haemoglobin (Hb for short). The function
of haemoglobin is to carry oxygen from the lungs to all
parts of the body.
People with Sickle Cell Anaemia have Sickle haemoglobin
(HbS) which is different from the normal haemoglobin (HbA).
When sickle haemoglobin gives up its oxygen to the tissues,
it sticks together to form long rods inside the red blood
cells making these cells rigid and sickle-shaped. Normal
red blood cells can bend and flex easily. Because of their shape, sickled red blood
cells can't squeeze through small blood vessels as easily
as the almost donut-shaped normal cells. This can lead to
these small blood vessels getting blocked which then stops
the oxygen from getting through to where it is needed. This
in turn can lead to severe pain and damage to organs.
Everyone has two copies of the gene for
haemoglobin; one from their mother and one from their father.
If one of these genes carries the instructions to make sickle
haemoglobin (HbS) and the other carries the instructions
to make normal haemoglobin (HbA) then the person has Sickle
Cell Trait and is a carrier of the sickle haemoglobin gene.
This means that this person has enough normal haemoglobin
in their red blood cells to keep the cells flexible and
they don't have the symptoms of the sickle cell disorders.
They do however have to be careful when doing things where
there is less oxygen than normal such as scuba diving, activities
at high altitude and under general anaesthetics.
If both copies of the haemoglobin gene
carry instructions to make sickle haemoglobin then this
will be the only type of haemoglobin they can make and sickled
cells can occur. These people have Sickle Cell Anaemia and
can suffer from anaemia and severe pain. These severe attacks
are known as Crises. Over time Sickle Cell sufferers can
experience damage to organs such as liver, kidney, lungs,
heart and spleen. Death can be a result.
Another problem is that red blood cells
containing sickle haemoglobin do not live as long as the
normal 120 days and this results in a chronic state of anaemia.
In spite of this, a person with sickle cell disorder can
attend school, college and work. People with sickle cell
disorder need regular medical attention particularly before
and after operations, dental extraction and during pregnancy.
Many hospitals arrange follow-up appointments and it is
advisable to discuss with the doctors questions concerning
schooling, strenuous exercise, family planning, suitable
types of employment and air travel. When a person is found
to have a sickle cell disorder it is important that all
members of the family be tested. They will not necessarily
have sickle cell disorder but may be healthy carriers of
a sickle cell trait.
Copyright© (www.sicklecellsociety.com)
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'Gentler' treatment for sickle
cell hailed
Patricia Guthrie - Staff
Friday, October 26, 2001 Atlanta Journal Constitution
A "kinder, gentler" new bone marrow transplant may
lead to the cure of more people with sickle cell disease.
Controlled studies of the therapy will begin in a
few months at 25 hospitals around the country, including
Children's Healthcare of Atlanta and Grady/Hughes
Spalding Children's Hospital.
Known as "partial chimerism," the procedure uses a
mixture of the patient's bone marrow and a donor's
bone marrow that combine to form healthy new blood
cells. It allows for a patient's bone marrow not to
be destroyed.
Currently, bone marrow transplants are of limited
use for people with sickle cell disease, because adults
and some children can't endure the procedure. Under
the new therapy, it will no longer be the goal to
totally wipe out and replace bone marrow, where red
and white blood cells and platelets are made.
"The new protocol is let's go ahead and aim for the
mixture so that it will allow transplants to be open
to more people," explained Dr. Lewis Hsu, a pediatric
sickle cell specialist at Emory University School
of Medicine who is affiliated with Children's Healthcare
and Grady's Sickle Cell Center. "This could be the
start of a very big step in the treatment of the disease."
Sickle cell disease, a genetic condition, affects
70,000 Americans, 95 percent of them African-American.
Between 4,000 and 6,000 Georgians suffer from it.
For some children with sickle cell disease, standard
bone marrow transplants using a patient's sibling
as a donor have provided a cure that long eluded doctors.
The treatment is no longer considered experimental
and has a success rate of 85 percent, doctors say.
More than 100 children have undergone the procedure
nationally, and the doctors at Children's Healthcare
of Atlanta have
performed more of the transplants than any other.
Eight-year-old Bryce Payton of Lithonia was given
a new life from the bone marrow of his big brother,
Chase, earlier this year. "He's 100 percent free of
sickle cells," said his father, Terrence Payton.
Bryce and Chase underwent the bone marrow transplant
March 1, the same day President Bush toured the AFLAC
Cancer Center and Blood Disorder Service at Egleston
hospital.
"He was actually in the room when the new bone marrow
was being infused into Bryce," Terrence Payton said
of Bush. "And he told his older brother what he did
made him a hero."
In the past, procedures such as the one Bryce endured
during a monthlong hospital stay would have been considered
a failure had his bone marrow not been eliminated
completely, or if it had come back with the crescent-shaped,
sticky, sickled red cells. It would have meant that
the bone marrow graft did not take hold.
But doctors in Seattle, Atlanta and Oakland, Calif.,
discovered that not to be true in five young patients.
They were deemed cured of the disease one year after
transplantation, even though their blood contained
some sickled cells. But they experienced none of the
typical infections or pain of the disease.
The mixed-blood partial chimerism therapy has proven
successful in other diseases as well. Mixing the two
bone marrows involves a delicate balance of acceptance
and tolerance.
"The host and donor blood tolerate each other, put
up with other and not reject each other," Hsu explained.
"It's making it kinder and gentler, maybe less
costly."
There are, however, risks with the new therapy. The
chances of graft rejection could be higher. Rejection
can be fatal or can lead to chronic graft-versus-host
disease that attacks skin, lungs and other organs.
Initially, only 30 children nationwide will receive
the new therapy. The results won't be known for at
least a year.
Also see: "Mixed Chimerism Following Bone Marrow
Transplantation-As Treatment For Sickle Cell Disease"
Children's Hospital Oakland - http://hemonc.cho.org
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