The Chromosomal Analysis
The chromosomal analysis of sickle cell disease is focused on beta-globin mutations. The disorder is provoked by the abnormal beta-globin alleles that are transmitting the sickle mutation on the hemoglobin subunit beta, or HBB gene (Glu6Val, βS) (Ware, de Montalembert, Tshilolo, & Abboud, 2017). Sickle cell disease is an inherited disorder, the most severe type of which is homozygous HbSS, or sickle cell anemia (Ware et al., 2017, p. 1). Sickle cell anemia occurs in case if a child inherits βS from both of the parents. Under such circumstances, the pathological sickle hemoglobin tetramer is being formed (α2βS2, HbS) (Ware et al., 2017). Other kinds of the disease are represented by compound heterozygous conditions:
- “hemoglobin C (HbC) with HbS (HbSC)”;
- “HbS with β-thalassemia (HbS/β0-thalassaemia or HbS/β+-thalassaemia)”;
- “HbS with other beta-globin variants such as HbSD or HbSOArab” (Ware et al., 2017, p. 1).
Each of these forms expresses enough HbS to provoke intracellular sickling. When a child inherits both HbA and HbS, he or she acquires a condition called sickle cell trait. Although it is not officially a form of sickle cell disease, it may be related to negative health outcomes (Ware et al., 2017).
The Causes of the Disorder
Sickle cell disease is generated by abnormal erythrocytes with the shape of a sickle. As a result of these erythrocytes’ obstruction of the flow of blood in small vessels, a person may develop inflammation or distal tissue ischemia (Ware et al., 2017). Sickle cell disease is an inherited illness. The complications include anemia, organ damage, meningitis, and hypoxia (Ware et al., 2017).
Origin of the Disorder
Sickle cell disease has a single gene inheritance (Ribeil et al., 2017). The disease is caused by a “homozygous missense mutation” in the beta-globin gene that leads to polymerization of hemoglobin S (Ribeil et al., 2017, p. 848). Beta-globin is one of the elements constituting hemoglobin. Hemoglobin contains two alpha-globin subunits and two beta-globin subunits. Mutations in the HBB lead to the creation of different forms of beta-globin. One of HBB gene mutations provoke an abnormal type of beta-globin called hemoglobin S. In individuals with sickle cell disease, hemoglobin S substitutes the minimum of one beta-globin subunit.
Sickle cell disease belongs to the most frequent inherited monogenic illnesses (Ribeil et al., 2017). This condition was the first to have the molecular basis established: “a single amino acid substitution in “adult” βA-globin (Glu6Val) stemming from a single base substitution (A→T) in the first exon of the human βA-globin gene” was explored in 1956 (Ribeil et al., 2017, p. 848). Sickle hemoglobin decreases the ability of red cells to deform through polymerization on deoxygenation (Ribeil et al., 2017). People suffering from sickle cell disease frequently experience vaso-occlusive crises that cause irrevocable damage to organs, low quality of life, and decreased life expectancy (Ribeil et al., 2017).
There is only one illness-modifying therapy accepted for sickle cell disease – hydroxyurea that can increase fetal hemoglobin amount in some people (Ribeil et al., 2017). The only curative choice is “allogeneic hematopoietic stem-cell transplantation” (Ribeil et al., 2017, p. 848). Still, only less than one-fifth of patients has a matched sibling donor (Ribeil et al., 2017). There is a high probability of reaching positive treatment results with the use of “therapeutic ex vivo gene transfer into autologous hematopoietic stem cells” (Ribeil et al., 2017, p. 848).
Considerations for Practice and Patient Education
There are some difficulties presented by the identification of pain as that of resulting from sickle cell disease (Matthie & Jenerette, 2015). Patients frequently complain of nurses’ insufficient knowledge of the illness and their inability to relieve the pain crises in a timely manner. As a result, it is crucial to develop a relevant care plan that would contain the most significant issues that should be known by nurses (Matthie & Jenerette, 2015). There are no objective signs of a sickle pain crisis, and every patient’s reaction to pain and coping techniques vary. Therefore, when creating a care plan, it is necessary to consult with patients as experts in their condition. It is crucial to arrange advocacy for patients because it will allow more efficient communication with medical workers (Matthie & Jenerette, 2015). With the help of care plans, nurses will be more aware of the peculiarities of the disease and will be able to give the most suitable care necessary for their patients to manage pain crises.
Another aspect of successful management of sickle cell disease is patient education and self-care (Matthie, Jenerette, & McMillan, 2015). As well as in any chronic condition, home management of the disease helps patients to prevent crises and relieve pain. The most significant aspects influencing patients’ level of self-care, as reported by Matthie et al. (2015) are social support, self-efficacy, and the number of years of education.
Patients should be instructed to contact their provider as soon as they notice any of the following:
- symptoms of a stroke: weakness in extremities, dizziness, difficulty speaking;
- signs of a heart attack: chest pain, vomiting, shortness of breath, discomfort in stomach, neck, or back;
- excessive tiredness;
- inability to think clearly;
- coughing up blood;
- hematuria;
- inability to cope with the pain (“Sickle cell disease,” n.d.).
The Gene Mutation of the Disease
Sickle cell disease is an inherited illness. The disease results from a single point mutation in “the seventh codon of the beta-globin gene” (Hoban et al., 2015, p. 2597). The most common characteristics of this condition are severe painful crises and anemia. Sickle cell disease is caused by a mutated variant of a gene that takes part in the production of hemoglobin – a protein the responsibility of which is carrying oxygen in red blood cells. When a person has two copies of the sickle cell gene, they have got the illness. When a person has only one copy of sickle cell gene, they have not got the illness but can pass it to their babies.
The mutation is called “homozygous missense,” and it takes place in the beta-globin gene (Ribeil et al., 2017, p. 848). As a result, hemoglobin S is polymerized, and it replaces at least of the four subunits of beta-globin (Ribeil et al., 2017). In order to reduce the detrimental impact of gene mutation leading to sickle cell disease, professionals work on the development of new therapeutic approaches. Sun and Zhao (2014) suggest the use of “disease-specific patient-derived human induced pluripotent stem cells” (hiPSCs) as a highly promising option for treatment of disorders induced by gene mutations (p. 1048). According to Sun and Zhao (2014), when the illness-causing mutations are corrected in place, patient-derived hiPSCs have the potential for renovating the functions of cells and acting as a renewable “autologous cell source” for the management of genetic illnesses (p. 1048). Therefore, sickle cell disease is caused by a single point mutation, and scientists are working on the development of relevant treatment methods to prevent the detrimental outcomes of the disorder.
References
Hoban, M. D., Cost, G. J., Mendel, M. C., Romero, Z., Kaufman, M. L., Joglekar, A. V., … Kohn, D. B. (2015). Correction of the sickle cell disease mutation in human hematopoietic stem/progenitor cells. Blood, 125(17), 2597-2604.
Matthie, N., & Jenerette, C. (2015). Sickle cell disease in adults: Developing an appropriate care plan. Clinical Journal of Oncology Nursing, 19(5), 562-268.
Matthie, N., Jenerette, C., & McMillan, S. (2015). Role of self-care in sickle cell disease. Pain Management Nursing, 16(3), 257-266.
Ribeil, J.-A., Hacein-Bey-Abina, S., Payen, E., Magnani, A., Semeraro, M., Magrin, E., … Cavazzana, M. (2017). Gene therapy in a patient with sickle cell disease. The New England Journal of Medicine, 376(9), 848-855.
Sickle cell disease. (n.d.).
Sun, N., & Zhao, H. (2014). Seamless correction of the sickle cell disease mutation of the HBB gene in human induced pluripotent stem cells using TALENs. Biotechnology and Bioengineering, 111(5), 1048-1053.
Ware, R. E., de Montalembert, M., Tshilolo, L., & Abboud, M. R. (2017). Sickle cell disease. The Lancet, 390(10091), 311-323.