A genetic disorder refers to a disease caused wholly or partially by changes in the sequence of the deoxyribonucleic acid (DNA) away from the normal sequence ("Genetic Disorders", 2018). Genetic diseases can be passed from generation to generation via inheritance of the genetic traits that run through families in distinct patterns. These patterns include dominant genetic disorders caused by mutations in a gene copy. It means that if the parent has a dominant gene, their children have a 50% chance of inheriting the disorder. The second pattern is through recessive genetic disorders, where both parents are carriers of the recessive disease. The third pattern is through sex-linked genetic disorders affecting both males and females differently. Complications from this pattern relate to mutations on the Y and X chromosomes. The last pattern is through multifactorial traits. These traits occur due to increased composite interactions and combinations related to maternal, environmental, and genetic influences ("Genetic Disorders", 2018) . Diseases such as sickle-cell are caused by mutations that people inherit from parents hence present to individuals at birth.
Sickle cell anemia refers to a disorder that occurs when the body abnormally produces red blood cells. These red blood cells possess a sickle shape. Additionally, they do not last like healthy red blood cells. The inheritance of the sickle cell anemia occurs through an autosomal recessive pattern; hence, it means that both parents possess a gene of a mutated gene ("Sickle cell anemia | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program", 2015). In normal instances, individuals inherit two replicas of the gene in humans that are essential in producing beta-globin that is a protein required by the body to produce hemoglobin in a normal way. The hemoglobin is referred to as hemoglobin A carrying the genotype AA (Serjeant, 2013). Individuals carrying sickle cell traits inherit a single normal allele while at the same time inheriting a single abnormal allele that encodes the hemoglobin S referred to as hemoglobin genotype AS.
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The symptoms of sickle cell anemia typically manifest in early childhood. People with this disease possess low numbers of red blood cells, they get infected repeatedly, and episodes of pain are evident periodically. Severity differs among individuals. With the sickling of the red blood cells, their breakdown occurs prematurely, causing anemia. Anemia in individuals causes breath shortness, and children grow and develop slowly ("Sickle cell disease", 2020). When red blood cells breakdown rapidly, it causes yellowing on the skin and the eyes of the victims hence, indicating jaundice. When painful episodes occur, they may deprive organs and tissues of oxygenated blood, causing damage to organs like the lungs, spleen, kidneys, and in the brain. Sickle cell diseases may lead to a severe complication of high blood pressure within blood carrying vessels causing pulmonary hypertension. As a result, in adults, it might cause heart failure. Other symptoms include weak vision and swelling of the hands and legs.
Human beings are diploid organisms meaning that they possess two alleles within a single autosomal locus. Combining these alleles, which have been inherited from the parents, makes the genotype of an individual. As a result, within the sickle cell locus, there exist two principal alleles: allele A and allele S. Any combination of these two alleles produces the genotype of and individual. The genotype AS is regarded as having a sickle cell trait phenotype with people having the genotype SS possess the phenotype of the disorder.
The disorder makes the red blood cells to break down and misshapen. This causes contortion within the red blood cells forming a crescent shape. When the cells die, they leave behind the deficiency of vigorous red blood cells that causes anemia ("Sickle cell anemia - Symptoms and causes", 2020). As a result, individuals fail to get sufficient oxygen within their bodies that's causes fatigue.
Possessing sickle cell disease disorder has an advantage to the victims. Researchers found out that in malaria-endemic regions, people having sickle cell traits, often regarded as heterozygotes, have survival advantages regarding fatality related to malaria than individuals having the normal hemoglobin. The trait in individuals causes significantly reduced deaths caused by malaria, mainly when the causative agent is the Plasmodium falciparum ("Mystery solved: How sickle hemoglobin protects against malaria", 2011).
Sickle cell disorder is regarded as a multisystem syndrome triggered by a mutation of a single gene. Any organ may be affected within the body (Piel, Steinberg & Rees, 2017). The existence of atypical erythrocytes damaged by homozygosity of the sickle hemoglobin (HbS), characterizes the disorder with the variant normal adult hemoglobin (HbA) in adults gets inherited by their children either from one or both the parents. Along with other variant hemoglobin like HbC (hemoglobin C). When HbS is deoxygenated, it polymerizes hence damaging the erythrocyte leading to loss of cations and water (Piel, Steinberg & Rees, 2017). After the cells get damaged, they get the abnormality within rheologic features causing hemolytic anemia. Additionally, it may cause a blockage within small blood vessels, which may lead to vaso-occlusion.
Over time, the sickle cell disease worsens in victims. In preventing complications and lengthening the lives of individuals with these conditions, treatments are applied and vary amid people in relation to their symptoms and severity. Hydroxyurea is a type of medicine used in decreasing sickle cell disease complications. Endari is also another drug that is another drug that is recommended by the Food and Drug Administration in reducing crises of the SCD in children over five years and in adults ("Complications and Treatments of Sickle Cell Disease | CDC", 2020). Stem cell transplant is another option used in treating the disease as it infuses healthy blood cells into the patients suffering sickle cell disease.
Additionally, engaging in light to moderate exercises appears to improve skeletal muscle microvasculature amid patients who have sickle cell disease. More so, eating fruits and vegetables with grains and proteins and nuts is helpful for patients with SCD. Foods rich in vitamin D, and calcium are highly recommended.
Internationally, over the years, millions of individuals have been infected with sickle cell disease. The disorder is commonly experienced amid individuals with ancestors originating from Africa, countries within the Mediterranean such as Greece, Italy and Turkey, Spanish speaking countries of South America, parts within the Caribbean, India, and the Arabian Peninsula ("Sickle cell disease", 2020). Due to the slave trade and the modern-day movement f the community, sickle cell disease distribution continues to spread to regions beyond its ancestries. As a result, in countries such as the United States of America, amid inherited blood disorders, Sickle cell disorder is ranked most common.
The Center for Disease Control and Prevention (CDC) states that approximately 100,000 Americans have sickle cell disease. Additionally, they say that in Black of African-American births, 1 out of 365 has SCD. In Hispanic-American Births, 1 out of 16300 individuals has SCD ("Data & Statistics on Sickle Cell Disease | CDC", 2019). Lastly, they state that amid Black or African-American babies, sickle cell trait is exhibited in 1 in every 13 babies. Sickle cell disorder is specific to places with high altitudes. It is because high altitudes are known to have low oxygen than at sea levels (Tewari et al., 2015). Due to a lack of oxygen, cells may sickle within individuals. It is hence recommended that individuals take plenty of water as well as other fluids as a way of reducing dehydration. Cold climates may also increase the severity of SCD. Exposure to cold causes vasoconstriction of blood vessels with the blood velocity being reduced (Tewari et al., 2015). As a result, the peripheries may hold increased deoxygenated blood; thus, red blood cells spend too much time within this deoxygenated blood. It hence causes vaso-occlusion due to the polymerization of the HbS.
References
Complications and Treatments of Sickle Cell Disease | CDC. Centers for Disease Control and Prevention. (2020). Retrieved 13 July 2020, from https://www.cdc.gov/ncbddd/sicklecell/treatments.html.
Data & Statistics on Sickle Cell Disease | CDC. Centers for Disease Control and Prevention. (2019). Retrieved 13 July 2020, from https://www.cdc.gov/ncbddd/sicklecell/data.html.
Genetic Disorders. Genome.gov. (2018). Retrieved 13 July 2020, from https://www.genome.gov/For-Patients-and-Families/Genetic-Disorders.
Mystery solved: How sickle hemoglobin protects against malaria. ScienceDaily. (2011). Retrieved 13 July 2020, from https://www.sciencedaily.com/releases/2011/04/110428123931.htm.
Piel, F., Steinberg, M., & Rees, D. (2017). Sickle Cell Disease. New England Journal Of Medicine, 376(16), 1561-1573. https://doi.org/10.1056/nejmra1510865
Sickle cell anemia | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program. Rarediseases.info.nih.gov. (2015). Retrieved 13 July 2020, from https://rarediseases.info.nih.gov/diseases/8614/sickle-cell-anemia.
Sickle cell disease. Genetics Home Reference. (2020). Retrieved 13 July 2020, from https://ghr.nlm.nih.gov/condition/sickle-cell-disease#.
Sickle Cell Anemia-Symptoms, Causes, and Symptoms. Aderonkebamidele.com. (2020). Retrieved 13 July 2020, from https://aderonkebamidele.com/sickle-cell-anemia-sy/.
Tewari, S., Brousse, V., Piel, F., Menzel, S., & Rees, D. (2015). Environmental determinants of severity in sickle cell disease. Haematologica, 100(9), 1108-1116. https://doi.org/10.3324/haematol.2014.120030
