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PubMed2001

Leukoreduction of sickle cell trait blood: an unresolved issue.

With the increasing demand for leukoreduction of blood components and the implementation of universal leukoreduction in several countries, the problems associated with leukocyte filtration of sickle cell trait blood have been revisited. Currently, there is no unified standard practice for sickle cell trait donors. Different blood centers adopt different policies. While some defer these donors from red cell component donation, some do not. Some screen all ethnic African donors for hemoglobin S (Hb S), others do not. Furthermore, there are differences in views of whether sickle cell trait red cells should be considered as equivalent to non-sickle cell trait red cells. Some blood centers do not give red cells from a sickle cell trait donor to the newborn or patients undergoing general anesthesia as a preventative measure. In this presentation, we discuss the epidemiology of the sickle gene, the sickling process, problems associated with leukoreduction of sickle cell trait whole blood and red cells, and some unresolved issues concerning donor referral and the usage of sickle cell trait blood.

Blood Donors↗
PubMed1979

Sickle cell trait and diabetic retinopathy.

The presence of sickle cell trait and the prevalence and severity of retinopathy were assessed in 124 Negro diabetics. Sickle cell trait had no adverse effect on diabetic retinopathy.

Adult↗
PubMed1989

Sickle cell trait revisited.

Variability in the clinical severity of sickle cell diseases is often genetically determined. Coexistent alpha-thalassemia decreases some, but not all, associated morbid complications. Polymorphisms within the beta-globin-like gene cluster influence disease severity by varying gamma-gene expression and the amount of Hb F within the cells. Few persons with the sickle cell trait experience adverse consequences attributable to the beta s gene. Is this also due to genetic factors? A literature search failed to answer this question. It is intriguing, however, that reported associations of sickle cell trait and splenic infarction have occurred exclusively in males and mostly in whites. Plausible but scanty data suggest that splenic infarction, hematuria, and reduced renal concentrating ability may be associated with higher amounts of Hb S. Therefore, alpha-thalassemia may be protective. No evidence was found that the amount of Hb S influenced the incidence of sudden death after exertion or that increased amounts of Hb F accounted for protection against any complications. More detailed reporting of biochemical and genetic evaluations of persons with sickle cell trait who experience related clinical events may lead to a better understanding of risks in subpopulations of persons carrying a single beta s gene.

Altitude↗
PubMed2000

Prenatal sickle cell screening education effect on the follow-up rates of infants with sickle cell trait.

OBJECTIVE: To assess the effect of prenatal education about newborn sickle cell screening on parents' compliance with the follow-up for infants with sickle cell trait. SUBJECTS: Expectant mothers whose prenatal education included information about newborn sickle cell screening were the study group, and those whose prenatal education did not include such information were the control group. METHODS: Mothers of infants with sickle cell trait were given the opportunity for in-person notification of screening results and follow-up counseling/education. Follow-up rates, anxiety and retention of information were assessed for the case-control study. RESULTS: There were a total of 15,670 infants born in the region, and 647 infants were identified with sickle cell trait. The follow-up rate for parents of infants with sickle cell trait was significantly higher (76%) for study group than the control group (49%) (P = 0.0006). Parents whose prenatal education included sickle cell hemoglobinopathy information retained significantly more of the information given during the post-natal education than did controls. CONCLUSION: Our data suggest that prenatal education for expectant mothers which includes information about newborn sickle cell screening significantly increases the follow-up rate for infants with sickle cell trait and contributes to a greater retention of information.

Adult↗
PubMed1990

Pulmonary embolism and splenic infarction in a patient with sickle cell trait.

A 43 year-old black man with sickle cell trait documented by hemoglobin electrophoresis presented with severe pleuritic chest pain and hypoxemia three weeks after discharge following abdominal surgery. A pulmonary embolus was diagnosed by angiography and he was treated with heparin; the minimum arterial pO2 was 55 torr while O2 was being administered at a rate of 3 L/min. During this therapy, he developed abdominal pain. Computerized tomography suggested splenic infarction, which was documented by radionuclide liver-spleen scan and magnetic resonance imaging (MRI); the patient's spleen had been normal at exploratory laparotomy three weeks previously. No source for emboli was identified in the deep venous system by MRI. Although splenic infarction has been reported in patients with sickle cell trait at high altitude, this is the first reported case of splenic infarction secondary to the hypoxemia of pulmonary embolism in a patient with sickle cell trait. The spleen is subject to infarction in sickle cell trait because blood flow is slow through a hypoxemic and acidemic environment. The additional hypoxemia due to pulmonary embolism is presumed, in our patient, to have created a local splenic environment which permitted infarction to occur.

Adult↗
PubMed2005

[Is the sickle-cell trait a risk factor?].

Generally the sickle-cell trait is not regarded as a risk factor for morbidity or mortality and consequently does not entail occupational restrictions on physical activity (except for military pilots or divers). However many reports have described cases of visceral infarction, disseminated intravascular coagulation, and sudden death. High altitude, strenuous exertion, dehydration and fever may increase the risk. For getting more date, the author propose a medical follow-up program for athletes and soldiers with sickle-cell trait and the implementation of a national registry for sudden deaths involving athletes.

Humans↗
PubMed2001

Latent proliferative sickle cell retinopathy in sickle cell trait.

PURPOSE: To describe a patient with sickle cell trait who developed latent proliferative sickle cell retinopathy after mild blunt trauma. METHOD: Case Report. A 20-year-old man with unilateral Stage 3 sickle retinopathy associated with an ischaemic ridge presenting three years after the initial mild blunt ocular trauma. RESULTS: Fundus examination of the left eye showed an ischaemic ridge delineating avascular from vascular retina. Fluorescein angiography of the left eye showed an avascular peripheral retina and multiple sea fan neovascularization. Blood studies showed him to be Hb AS. CONCLUSIONS: In our patient the proliferative changes were the result of his initial mild trauma associated with an increase in the intraocular pressure. The latent development of the sea-fan neovascularization associated with an ischaemic ridge is unusual. Advice about potential complications to patients with Hb AS after ocular trauma is advocated.

Eye Injuries↗
PubMed1977

Proliferative retinopathy in sickle cell trait. Report of seven cases.

Seven patients had sickle cell trait (hemoglobin AS) and vasoproliferative retinopathy. The retinal abnormalities in these seven patients were indistinguishable from those seen in patients with clinically significant sickling hemoglobinopathies (sickle cell-hemoglobin C disease, hemoglobin S-thalassemia disease, and sickle cell anemia). All seven patients also had some evidence of associated systemic disease such as diabetes, syphilis, tuberculosis, or sarcoidosis. In the presence of an associated systemic disease, marked retinopathy can occur in the ordinarily benign condition of sickle cell trait.

Adult↗
PubMed1997

Women with sickle cell trait are at increased risk for preeclampsia.

OBJECTIVE: Our purpose was to determine the rate of preeclampsia in women who are positive for sickle cell trait. STUDY DESIGN: All African-American women were tested for sickle cell trait with the "sickledex" screen at the fist prenatal visit and prospectively enrolled in this study from March 1994 to June 1995. "Sickledex" screens were confirmed with hemoglobin electrophoresis. Demographic data were collected at the time of enrollment. Outcome data, including preeclampsia (as defined by The American College of Obstetricians and Gynecologists criteria), gestational age at delivery, birth weight, and postpartum endometritis were collected immediately post partum. Assuming a 10% rate of positive sickle cell trait, 1100 patients were required to demonstrate a doubling in the rate of preeclampsia with 80% power and p < 0.05. The Student t test, the Mann-Whitney U test, chi 2 analysis, and Fisher's exact tests were used for statistical analysis. RESULTS: Of 1584 women enrolled in the study, 162 were positive for sickle cell trait. Sickle cell trait-positive women were older than the sickle cell trait-negative women (24.4 +/- 4.6 vs 23.0 +/- 4.4 years, p < 0.001), but there was no significant difference in parity. The rate of preeclampsia was significantly increased in sickle cell-positive women (24.7% vs 10.3%, p < 0.0001). There was no significant difference in the rate of chronic hypertension, diabetes, or smoking. Parous sickle cell-positive women more frequently gave a history of preeclampsia in a previous pregnancy (21.4% vs 9.3%, p < 0.0001). There was a statistically significant decrease in gestational age at delivery and birth weight in sickle cell trait-positive women (36.7 +/- 2.7 vs 37.7 +/- 3.0 weeks, p < 0.0001; and 3082 +/- 591 vs 3369 +/- 573 gm, p < 0.0001). The rate of postpartum endometritis was significantly increased in the women positive for sickle cell trait (12.3% vs 5.1%, p < 0.001), although both groups had a similar cesarean section rate (14.8% vs 12.6%, not significant). CONCLUSION: This is the first prospective study to demonstrate that sickle cell trait-positive women are at significantly higher risk for development of perinatal complications that have traditionally been associated with sickle disease.

Adult↗
PubMed1993

Direct demonstration that the A gamma T globin gene is linked to the 4 bp promoter deletion in the beta A chromosome of sickle cell traits.

In beta zero-thalassemia and sickle cell patients, a 4 bp deletion at -222 to -225 of the A gamma globin promoter was associated with low expression of the A gamma T variant (threonine at codon 75 of A gamma), whereas A gamma I (isoleucine at 75) had the normal A gamma promoter and higher expression. However, it has been reported that the beta A chromosomes of sickle cell trait cases have the 4 bp deletion as a common polymorphism unlinked to the A gamma T allele. We now present data demonstrating the association of the A gamma T allele with the 4 bp deletion in beta A chromosomes of sickle cell traits.

Alleles↗
PubMed1980

Renal response to potassium loading in sickle cell trait.

Anatomical and functional renal medullary abnormalities are common in patients with sickle cell disease (HbSS) and sickle cell trait (HbAS). Sickle cell disease is associated with impaired urinary potassium excretion, but renal potassium handling in patients with HbAS has not been reported. To address this question, we gave nine HbAS and eight black control (HbAA) volunteers an oral potassium chloride load (0.75 mEq/kg of body weight), collected urine for five hours, and measured changes in the serum and urinay potassium levels. Both prior to and after potassium chloride loading, there were no differences between groups in serum or urinary potassium levels nor in percent of excretion of administered potassium. We conclude that patients with HbAS, despite decreased concentrating ability, have no impairment of the renal response to oral potassium loading and no apparent increased risk of hyperkalemia during periods of high potassium intake.

Adolescent↗
PubMed2000

Maternal sickle cell trait and fetal hypoxia.

Patients with sickle cell trait (SCT) usually run a benign course. But they may develop vaso-occlusive crisis, which may lead to hypoxia. During these episodes, pregnant women with SCT may effect the developing fetus. This report describes an interesting finding of subtle degree of fetal hypoxia associated with maternal SCT. Twenty mothers with SCT were compared with 20 controls for the amount of circulating nucleated red blood cells (NRBC) and marker of fetal hypoxia at birth. Elevated number of circulating NRBC were noted in the cord blood of neonates born to mother with SCT as compared with controls, suggesting evidence of intrauterine fetal hypoxia. A larger prospective study is needed to elaborate further on this association.

Adolescent↗
PubMed2006

Red blood cells from donors with sickle cell trait: a safety issue for transfusion?

Sickle cell trait (SCT) affects approximately 8% of the population in Martinique (FWI) and about the same rate is found among the African Americans. In several regions of tropical Africa, up to 40% of individuals are also affected. SCT has been characterized as a benign condition and patients are currently asymptomatic or run a benign course. However, life-threatening complications may occur. SCT can be detected in patients hospitalized for various complaints, and SCT likely causes serious morbidity and mortality in some people. Moreover, these clinical observations have been supported by several in vitro studies in which haemoglobin AS red cells showed abnormalities of their filterability. These problems are revisited with the implementation of universal leucoreduction in several countries. The question of the screening of all blood donors for SCT and the use of their red blood cells (RBCs) has yet to be resolved.

Blood Donors↗
PubMed1998

[Splenic infarct in heterozygote sickle cell trait (Hb AS)].

We present a carrier of the sickle cell trait who developed a serious splenic infarction. An antecedent hypoxaemic event and a blood coagulation disorder were ruled out. The observation shows that the sickle cell trait can represent a risk factor for a life-threatening thrombotic event, even in the absence of a predisposing condition.

Adult↗
PubMed2005

An immune basis for malaria protection by the sickle cell trait.

BACKGROUND: Malaria resistance by the sickle cell trait (genotype HbAS) has served as the prime example of genetic selection for over half a century. Nevertheless, the mechanism of this resistance remains the subject of considerable debate. While it probably involves innate factors such as the reduced ability of Plasmodium falciparum parasites to grow and multiply in HbAS erythrocytes, recent observations suggest that it might also involve the accelerated acquisition of malaria-specific immunity. METHODS AND FINDINGS: We studied the age-specific protection afforded by HbAS against clinical malaria in children living on the coast of Kenya. We found that protection increased with age from only 20% in the first 2 y of life to a maximum of 56% by the age of 10 y, returning thereafter to 30% in participants greater than 10 y old. CONCLUSIONS: Our observations suggest that malaria protection by HbAS involves the enhancement of not only innate but also of acquired immunity to the parasite. A better understanding of the underlying mechanisms might yield important insights into both these processes.

Age Factors↗
PubMed1996

Exertional collapse and sudden death associated with sickle cell trait.

The most serious complication of sickle cell trait (SCT) is sudden death during exertion. SCT often remains unrecognized in the 2.5 million African Americans affected. Exertional collapse and sudden death associated with SCT is characterized by rhabdomyolysis, heat stroke, and cardiac arrhythmia. There is a 40-fold increased risk of sudden death in affected soldiers during military basic training and there are many cases reported in athletes during preseason training. There have been no cases reported in soldiers beyond basic training. In the case presented, a soldier with 3 years of military service succumbed to SCT-associated sudden death during physical fitness testing.

Adult↗
PubMed1996

Is there increased fertility in adult males with the sickle cell trait?

Different proposals have been offered to explain the polymorphism of the sickle cell hemoglobin gene. One of these proposals (Eaton and Mucha 1971) suggested that differential fertility of male subjects with the sickle cell trait contributes to the persistence and stability of the sickle cell gene frequency. Eaton and Mucha claimed that oligospermia, induced by hyperpyrexia, is a less common problem in these subjects because they probably have milder and shorter episodes of fever from malaria infection than subjects with a normal genotype. We have looked for evidence to support this hypothesis by comparing the testicular function, testicular size, and serum concentrations of the reproductive hormones in adult male subjects with the sickle cell trait and in an age-matched group of subjects with normal hemoglobin genotype. The mean serum concentration of testosterone, luteinizing hormone, follicle-stimulating hormone, and prolactin of both groups, measured by radio-immunoassay, were not statistically different from each other. Also, there was no detectable difference in any of the common indexes of semen quality between the two groups. The testicular volume index and several anthropometric indexes of subjects with the sickle cell trait and subjects with the normal hemoglobin genotype were also statistically similar. The results suggest that gonadal function is similar in adult males with the normal genotype and those with the sickle cell trait. Any increase in fertility observed in the latter group is probably due to extragonadal factors.

Adult↗