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Sickle cell disease (SCD), also simply called sickle cell, is a group of hemoglobin-related blood disorders that are typically inherited. [2] The most common type is known as sickle cell anemia. [2] Sickle cell anemia results in an abnormality in the oxygen-carrying protein haemoglobin found in red blood cells. [2]
Those who are heterozygous for the sickle cell allele produce both normal and abnormal hemoglobin (the two alleles are codominant with respect to the actual concentration of hemoglobin in the circulating cells). Sickle cell disease is a blood disorder wherein there is a single amino acid substitution in the hemoglobin protein of the red blood ...
Autosomal dominant A 50/50 chance of inheritance. Sickle-cell disease is inherited in the autosomal recessive pattern. When both parents have sickle-cell trait (carrier), a child has a 25% chance of sickle-cell disease (red icon), 25% do not carry any sickle-cell alleles (blue icon), and 50% have the heterozygous (carrier) condition. [1]
Since HbC does not polymerize as readily as HbS, there is less sickling in most cases. There are fewer acute vaso-occlusive events and therefore in some cases fewer sickle cell crises. The peripheral smear demonstrates mostly target cells, occasional hemoglobin C crystals, and only a few sickle cells.
Photomicrograph of normal-shaped and sickle-shape red blood cells from a patient with sickle cell disease. Sickle cell anemia is a genetic disease that causes deformed red blood cells with a rigid, crescent shape instead of the normal flexible, round shape. [29] It is caused by a change in one nucleotide, a point mutation [30] in the HBB gene.
Note the irregularly shaped, non-circular cells in the image. Acanthocyte (from the Greek word ἄκανθα acantha, meaning 'thorn'), in biology and medicine, refers to an abnormal form of red blood cell that has a spiked cell membrane, due to thorny projections. [1] [2] A similar term is spur cells.
These elliptical cells are taken up by the spleen and removed from circulation when they are younger than they would normally be, meaning that the erythrocytes of people with hereditary elliptocytosis have a shorter than average life-span (a normal person's erythrocytes average 120 days or more).
An example of a genetic factor causing disease resistance is incomplete penetrance. Incomplete penetrance is the result of a genetic mutation not fully manifesting as the associated trait or disease. In the combined case of sickle cell anemia and malaria, individuals with one normal allele and one sickle cell allele, (heterozygous HbAS), are ...