The levels of HbS in people with sickle cell trait are largely genetically determined. This means that although their red blood cells contain some HbA, a portion of their red blood cells (20%-45%) consists of HbS. Select a genotype (ie, AA, no sickle cell disease AS, sickle cell trait carrier or SS, sickle cell disease) for both the male and female, then select “View Results” to see the chances of a child inheriting sickle cell trait or sickle cell disease.Ī person who carries the sickle cell trait inherits one copy of an abnormal (sickle) HBB gene Abnormal (sickle) HBB gene a gene mutation that produces hemoglobin S, which causes red blood cells to sickle and one copy of a normal HBB gene HBB gene Gene that provides cells with instructions for making a protein called β‑globin (beta-globin). However, you can create your own Punnett square by following the format below and using a different genotype (such as hemoglobin SC or hemoglobin S beta-zero) in place of “SS”. Note that the “sickle cell disease” selection for this tool is for the most common type of sickle cell, hemoglobin SS. This Punnett square can help you see how genes can be passed from a parent to a child in every single pregnancy, regardless of the genotypes of previous children. Use the interactive diagram below, called a Punnett square, to see the likelihood of a child inheriting a form of sickle cell disease or sickle cell trait. These different forms are described as your sickle cell genotype.
As a result, there is more than one type of sickle cell, which depends on the specific combination of alterations of the HBB gene you inherit. Scientists have identified hundreds of variations in the HBB gene that cause abnormal beta-globin to form and cause disease. Sickle cell disease is caused by inheriting two copies (one from each parent) of an altered HBB gene, which causes the production of an abnormal form of beta (β)-globin, such as hemoglobin S (HbS). This pair of genes is known as a genotype. In addition, serologic barriers pose enduring roadblocks to the optimization of transfusion therapy for patients with SCD, and the syndrome of massive hemolytic transfusion reactions and hyperhemolysis in SCD persists as a life-threatening complication for which appropriate clinical management is not yet defined.Genes usually come in pairs: one copy of a gene comes from each biological parent.
However, much remains unknown and areas of controversy persist. Years of unsystematic clinical observations, followed by more carefully designed and in some cases randomized studies, have contributed substantially to our knowledge of transfusion therapy in SCD. Thus, it is important to understand the indications for and goals of transfusion therapy and to be aware of the potential side effects of therapy. However, transfusion therapy for SCD may incur special and distinctive adverse effects. Sickle cell disease (SCD) is associated with red blood cell (RBC) abnormalities and moderate to severe anemia, and blood transfusion is naturally a mainstay of treatment.
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