Human Genetics, Sickle Cell Anemia

Introduction

Sickle cell anemia is a group of hereditary disorders that affect the red blood cells. People who have the disease have abnormal hemoglobin, which reduces their ability and capacity to abide oxygen to the body cells and organs. Sickle cell anemia is inherited from parents to the children. The condition is not contagious which means it cannot be transmitted through physical association with a person suffering from sickle cell anemia. The major problem with the sickle cell condition is that given red blood cells do not live long compared to the normal ones, which further reduces their capacity to carry oxygen. Further, the sickle cell red blood cells can stick in the vessels, which may lead to other health complications. Sickle cell anemia is a lifelong condition, but it can be managed using long-term treatment (Steinberg & Sebastiani, 2012).

Types of inheritance in sickle cell anemia

Sickle cell anemia is a recessive condition, which means that two cells affected by the sickle cell disease have to be inherited from both the parents. During fertilization, each parent contributes a specific gene for the child. In this case, for a child to inherit sickle cell anemia parents have to contribute a sickle cell trait to the child’s genes. However, those who possess only one single sickle cell hemoglobin gene from one parent and a normal copy of hemoglobin are said to have a sickle cell trait, and they can pass it to their children although they will not have sickle cell anemia (Jamieson & Radick, 2013).

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Incomplete dominance

The interactions of different alleles lead to different functions and condition. In sickle cell anemia, a person with homozygous recessive (ss) for sickle cell trait will have red blood cells with defective hemoglobin. On the other hand, an individual with homozygous but dominant genes (SS) will have normal blood cells. Therefore, an individual with both the recessive and dominant genes will have both abnormal cells and normal cells expressed equally which is referred to as incomplete dominance (Abraham et al., 2014).

Sex Linked Disorders

Sex linked disorders are the ones that occur due to a defect in the inherited X chromosome that causes diseases. Sickle cell anemia is inherited through autosomal or non-sex chromosomes because it is a recessively inherited disease and both parents contribute in passing the defective gene to the child (Serjeant, 2013). The symptoms of sickle cell anemia include an inadequate number of red blood cells also known as anemia, fatigue, shortness of breath, and the yellowing of the skin. Over a period of time, the poor oxygen delivery due to sickle cell anemia leads to organ damage. Antibiotics such as penicillin and over the counter pain relievers can be used to treat sickle cell anemia symptoms. Blood transfusion and oxygen therapy are also approaches that can be used to manage sickle cell anemia (Jamieson & Radick, 2013).

In conclusion, sickle cell anemia condition is hereditary in that a person inherits a pair of defective hemoglobin genes from both of the parents. Cases of incomplete dominance exist in sickle cell anemia and are referred to as sickle cell trait. Individuals with sickle cell traits do not show sickle cell anemia symptoms. The condition leads to poor oxygen supply because the number of the red blood cells is low and they are sickle shaped reducing the capacity to carry blood. Long-term treatment can be used to ease the symptoms of sickle cell anemia such as the use of antibiotics and painkillers.

 

References

Abraham, J. K., Perez, K. E., & Price, R. M. (2014). The Dominance Concept Inventory: a tool for assessing undergraduate student alternative conceptions about dominance in Mendelian and population genetics. CBE-Life Sciences Education, 13(2), 349-358.

Jamieson, A., & Radick, G. (2013). Putting Mendel in his place: how curriculum reform in genetics and counterfactual history of science can work together. The Philosophy of Biology, 577-595.

Serjeant, G. R. (2013). The natural history of sickle cell disease. Cold Spring Harbor perspectives in medicine, 3(10), a011783.

Steinberg, M. H., & Sebastiani, P. (2012). Genetic modifiers of sickle cell disease. American Journal of Hematology, 87(8), 795-803.