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Sickle Cell Disease
Published in Vincenzo Berghella, Maternal-Fetal Evidence Based Guidelines, 2022
Sickle cell disease describes a group of inherited disorders characterized by the presence of HbS. Sickle cell disease is associated with a mild to moderate chronic anemia. The term sickle cell disease includes sickle cell anemia (HbSS) (70% of cases), hemoglobin S combined with hemoglobin C (HbSC) (most of the remaining cases), hemoglobin S combined with β-thalassemia (HbSβ+ or HbSβ0), and other double heterozygous conditions causing sickling and thus, clinical disease (e.g., hereditary persistence of fetal hemoglobin (HgS/HPHP), and hemoglobin E (HbS/HbE) [7]. The clinical manifestations vary among these genotypes, with HbSβ0 usually with a similar severe phenotype as HbSS, HbSC associated with intermediate disease, and HbSβ+, HbSHPHP, and HbSE with mild or symptom-free disease [1, 5]. The term sickle cell anemia includes HbSS, and also HbSβ0 (due to its similar phenotype). The sickle cell trait is the heterozygous inheritance of HgbS and is characterized by benign clinical course without anemia, with protection against malaria [8].
Carrier Screening For Inherited Genetic Conditions
Published in Vincenzo Berghella, Obstetric Evidence Based Guidelines, 2022
Whitney Bender, Lorraine Dugoff
Sickle cell disease refers to a group of autosomal recessive disorders involving hemoglobin S. Hemoglobin S differs from hemoglobin A due to a single nucleotide substitution in the beta-globin gene on chromosome 11. The most severe form of sickle cell disease, sickle cell anemia, occurs in individuals with two copies of hemoglobin S. Sickle cell disorders can also occur in individuals who have hemoglobin S and another abnormality of B-globin structure or production such as hemoglobin C or beta-thalassemia. Sickle cell disease occurs most commonly in people of African origin. One in 12 African Americans has sickle cell trait. Patients with sickle cell disease are prone to distortion, or sickling, of their red blood cells under conditions of decreased oxygen tension. These distorted cells can result in increased viscosity, hemolysis, and anemia, resulting in interrupted blood supply to vital organs. These vasoocclusive crises can cause interruption of normal perfusion and function of several organs, including the spleen, lungs, kidney, heart, and brain. See Chap. 15 in Maternal-Fetal Medicine Evidence Based Guidelines.
Host Defense II: Acquired Immunity
Published in Constantin A. Bona, Francisco A. Bonilla, Textbook of Immunology, 2019
Constantin A. Bona, Francisco A. Bonilla
In red blood cells of patients with sickle cell trait, parasites induce sickling. The sickled cells are rapidly cleared from the circulation in the spleen, aborting the parasite life cycle. Sickling may also kill the parasites directly. In hemoglobin C disease, cells are very resistant to lysis and the merozoites cannot escape to propagate the infection. Hemoglobin E (possibly the most common mutant human hemoglobin) leads to erythrocyte resistance for replication and rapid clearance of infected cells. In hereditary persistence of fetal hemoglobin the fetal hemoglobin retards growth of Plasmodia. Ovalocytes (erythrocytes with altered membrane structure occurring in individuals with hereditary ovalocytosis) are resistant to penetration by P. falciparum. In glucose-6-phosphate dehydrogenase deficiency erythrocytes are resistant to plasmodium replication, possibly because the parasite requires the host enzyme. Epidemiologic and population studies strongly suggest a protective effect of various thallassemias in malaria, but the mechanism is not known.
HIV-1 infection in sickle cell disease and sickle cell trait: role of iron and innate response
Published in Expert Review of Hematology, 2022
Sickle cell disease (SCD) is an inherited hemoglobinopathy in which mutations in the β-globin gene (HBB) lead to the production of mutated hemoglobins of which the most prevalent are hemoglobin S (HbS, Glu6Val mutation) and hemoglobin C (Glu6Lys mutation) [1]. HbS polymerizes under low oxygen conditions leading to sickling of red blood cells (RBCs) and development of sickle cell anemia (SCA) that is characterized by hemolysis, vaso-occlusion and ischemia [2]. Clinical manifestations of SCA include recurrent pain crises and development of chronic organ damage caused by stroke, osteonecrosis, nephropathy, pulmonary disease and retinopathy [3]. SCA has also been associated with the increased risk of pulmonary hypertension, renal dysfunction, proteinuria, stroke and the overall increased mortality [4–9]. Other risk factors of SCA include left ventricular diastolic dysfunction, asplenia, cholestatic hepatic dysfunction and systemic iron overload [4,10]. SCD affects approximately 100,000 people in the U.S.A, primarily African Americans [11], and several million Africans, primarily in sub-Saharan Africa [2]. Worldwide, over 300,000 newborns in 2010 had SCD (75% in Sub-Saharan Africa) and by 2050 this number is expected to reach 400,000 [12].
Ocular Manifestations of Sickle Cell Disease in Different Genotypes
Published in Ophthalmic Epidemiology, 2021
Saif Aldeen AlRyalat, Bahaa Al-Din Mustafa Jaber, Abdulaziz A. Alzarea, Abdullah A. Alzarea, Wejdan A. alosaimi, Mouna Al Saad
Sickle cell disease (SCD) is a multisystemic disorder caused by a single gene mutation, causing red blood cells to assume a rigid sickle shape under certain circumstances.1 The most common variants in sickle cell disease are the homozygous SS and the heterozygous SC genotypes. These variants are caused by the presence of either 2 copies of the mutated hemoglobin S (HbS) allele, or a one copy of the HbS allele and another hemoglobin C (HbC) allele.2 Generally, patients with HbS homozygous genotype exhibit clinically more severe complications compared to other genetic variants,1 this logical finding was contradicted by a paradox that the SC genotype exhibits higher incidence of retinitis proliferans, osteonecrosis, and acute chest syndrome.3 Although sickle cell disease can affect any part of the eye, it mainly targets the conjunctiva, manifesting as characteristic comma-shaped conjunctival vessels known as “conjunctival sign”,4 the iris, manifesting as iris atrophy,5 and the retina where it is classified into proliferative and non-proliferative sickle cell retinopathy.1
Refractory acquired thrombotic thrombocytopenic purpura in a patient with sickle cell trait successfully treated with caplacizumab
Published in Hematology, 2021
Vibhuti Aggarwal, Zachary Singer, Donna Ledingham, Ibraheem Othman
The co-existence of published cases of TTP and sickle cell disease or sickle cell trait is very rare (Table 1). In our literature review there have been six reported cases of patients with sickle cell disease or sickle cell-hemoglobin C disease also presenting with TTP [9–14]. There have also been three cases of TTP diagnosed in a patient with sickle cell thalassemia [15–17]. However, there has only been one reported case of TTP in a patient with sickle cell trait [18]. It should be noted that these diagnoses of TTP were made clinically and based on the response to plasma exchange (PEX) rather than the measured ADAMTS13 deficiency. We chose to omit cases that had a documented normal ADAMTS13 level, as these likely represent other etiologies of thrombotic microangiopathy.