Sickle cell disease is an inherited condition in which the body is unable
to produce normal hemoglobin. Red blood cells with abnormal hemoglobin can
change shape in the presence of low oxygen levels and form "sickle" cells,
which don't fit through tiny capillaries well. During periods of stress or
exertion, the cells can become lodged in narrow blood vessels, blocking
oxygen delivery to organs and tissues. When this happens, patients
experience episodes of extreme pain during which oxygen-deprived organs and
tissues can be damaged.
Over time, repeated episodes of oxygen deprivation deteriorate the body.
But with improved care, most sickle cell patients are living well beyond
childhood. About one-half of all patients live to be at least 50 years old.
Because the cells have an abnormal shape, they are disposed of faster than
the body can replace them. Because patients lack a sufficient number of red
blood cells, they often develop "anemia."
From infancy, sickle cell patients face a host of complications involving
infections, stroke, and organ damage and failure.
Children whose parents both carry the gene for sickle cell are at risk of
inheriting the disease. Two copies of the gene, one from each parent, must
be present in order for the disease to manifest itself. If a child has only
one gene, he or she has sickle cell "trait," which usually causes no health
The gene is prevalent in people from Africa and parts of India and the
Mediterranean. The sickle cell gene also is found in people from South and
Central America, the Caribbean and the Middle East.
About one in every 500 African-American children and one in every 1,000 to
1,400 Hispanic-American children are born with sickle cell disease, and one
in 12 African-Americans has sickle cell trait.
Symptoms usually begin to appear during an infant's first year. Common
symptoms include fever; swelling of the hands and feet; pain in the chest,
abdomen, limbs and joints; enlargement of the heart, liver and spleen;
nosebleeds; and frequent upper respiratory infections.
As patients grow older they can develop symptoms of anemia - fatigue,
irritability, jaundice (yellowish discoloration of the skin and eyes),
pain, delayed puberty, leg sores, eye problems and gum disease.
Patients also encounter episodes of pain known as sickle cell crises.
During a crisis, patients experience shortness of breath, nausea, low-grade
fever, jaundice and severe pain in the fingers, toes, arms, joints, legs,
back, abdomen or bones.
During a crisis, blockage of blood and oxygen to the chest and lungs may
lead to acute chest syndrome. Damage to the lungs causes severe pain and
fever, and produces an abnormal chest X-ray. The lungs' airways narrow,
further reducing oxygen delivery. All this leads to an increased risk for
infections, which can be fatal.
Male patients may also suffer from priapism - painful and prolonged erections.
Treating sickle cell involves:
1. Medications to manage pain, inflammation, infections and anemia. During
a crisis, fluids may be administered to maintain fluid balance.
2. Oxygen to alleviate the effects of acute chest syndrome.
3. Blood transfusions to replace the patients' blood with donor blood.
Normal blood cells of the donor blood alleviate symptoms by transporting
needed oxygen to affected organs and tissues.
Recent studies have found that the anti-cancer drug hydroxyurea reduces the
frequency of painful crises and of acute chest syndrome in adult patients.
However, scientists are still studying the drug's long-term side effects.
Bone marrow transplant is only performed in specific cases. Donors must be
matched sibling donors, but fewer than one in five sickle cell anemia
patients have a matched sibling.
Therapies that aim to cure and treat the disease itself are now being
studied. Methods include gene therapy and drugs that prevent the cells from
taking on an abnormal shape, as well as drugs that stimulate the body to
produce more fetal hemoglobin, which does not cause red blood cells to sickle.
Sickle cell disease cannot be prevented. Couples who carry the gene should seek genetic counseling to determine their risk of bearing children with the disease.
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