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At the time it was a scientific puzzle that the disease was prevalent even though it killed people before they reached puberty, before they can have children to pass on the lethal gene. [4] He found that the prevalence of sickle-cell trait (heterozygous condition) among people inhabiting coastal areas was higher than 20%. [8]
It is possible for a person to have both the gene for hemoglobin S (the form associated with sickle cell anemia) and the gene for hemoglobin C; this state is called hemoglobin SC disease, and is generally more severe than hemoglobin C disease, but milder than sickle cell anemia.
Proliferative sickle retinopathy is the most severe ocular complication of sickle cell disease. Even though PSCR begins in the first decade of life, the condition remains asymptomatic and unnoticed until visual symptoms occur due to vitreous hemorrhage or retinal detachment.
The pathogen that causes the disease spends part of its cycle in the red blood cells and triggers an abnormal drop in oxygen levels in the cell. In carriers, this drop is sufficient to trigger the full sickle-cell reaction, which leads to infected cells being rapidly removed from circulation and strongly limiting the infection's progress.
Until the early 1950s, hemoglobin A and some of its variants had been identified, such as hemoglobin S and hemoglobin C.Hemoglobin D was discovered in 1951 with one source stating it was the third variant discovered, [2] and another source claiming it was the fourth. [1]
Autosplenectomy can occur in cases of sickle-cell disease where the misshapen cells block blood flow to the spleen, causing scarring and eventual atrophy of the organ. [2] Autosplenectomy is a rare condition that is linked to certain diseases but is not a common occurrence. It is also seen in systemic lupus erythematosus (SLE).
Thalassemias are inherited blood disorders that result in abnormal hemoglobin. [7] Symptoms depend on the type of thalassemia and can vary from none to severe. [1] Often there is mild to severe anemia (low red blood cells or hemoglobin) as thalassemia can affect the production of red blood cells and also affect how long the red blood cells live. [1]
Splenic sequestration crisis is a life-threatening illness common in pediatric patients with homozygous sickle cell disease and beta thalassemia. Up to 30% of these children may develop splenic sequestration crisis with a mortality rate of up to 15%.