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PubMed2003

Retinopathy in sickle cell trait: does it exist?

BACKGROUND: Patients with sickle cell trait and concomitant systemic disease are known to be at risk for proliferative retinopathy. However, there are reports of retinopathy in patients with sickle cell trait without systemic disease. There are no population-based studies addressing the risk of sickle cell retinopathy in this group. We performed a study to clarify the relation between sickle cell trait and retinopathy in healthy subjects. METHODS: We reviewed the medical records of 100 children with sickle cell disease who attended the Sickle Cell Clinic at the Hospital for Sick Children, Toronto. We then contacted 200 parents with sickle cell trait, of whom 32 agreed to participate in the study. All participants were proven to have hemoglobin AS status with prior hemoglobin electrophoresis. An ophthalmologic history was obtained, and a complete ophthalmologic examination was performed. We defined sickle cell retinopathy as any salmon patch hemorrhages, iridescent spots, black sunbursts, retinal neovascularization or retinal detachment. The evaluation also included attempts to identify the more subtle signs of sickle cell retinopathy, such as optic nerve head vascular changes, vascular tortuosity, macular changes (e.g., microaneurysms and vascular loops) and peripheral arteriovenous anastamoses. Blood samples were obtained for complete blood count, reticulocyte count and smear. RESULTS: We found no cases of sickle cell retinopathy among the 32 subjects. Ten of 30 subjects had a high reticulocyte count (greater than 120 x 10(9)/L); however, there were no associated eye findings in this subgroup. INTERPRETATION: Our results indicate that there is no increased risk of retinopathy in healthy people with sickle cell trait.

Adult↗

PubMed1984

Indications for surgical management of hyphema in patients with sickle cell trait.

We analyzed 22 sickle cell trait hyphemas. Fourteen of the 22 eyes were adequately controlled with medical therapy alone, ie, the intraocular pressure averaged less than 25 mm Hg during consecutive 24-hour periods and there were no repeated transient rises of IOP above 30 mm Hg. Surgery was performed in eight eyes, because of inadequate medical control. Thirteen of the 14 medically treated eyes had acceptable levels of IOP within the first 24 hours; only one of the eight surgically treated eyes had adequate control during the first 24 hours. This suggests that control during the first 24 hours portends a good prognosis, while lack of control during that period predicts continued difficulty managing the IOP. This seems to be important in view of previous experience that suggests that these eyes do not tolerate minimal to moderate elevations in IOP as well as those of patients without sickle cell anemia.

Anemia, Sickle Cell↗

PubMed1993

Cardiopulmonary function in men with sickle cell trait who reside at moderately high altitude.

Sickle cell trait has been associated with an unexplained increased risk of sudden death during military basic training. Previous studies of cardiopulmonary function in persons with sickle cell trait at sea level or after brief exposure to moderately high altitude have not shown significant abnormalities. To determine whether cardiopulmonary function is impaired in men with sickle cell trait who chronically reside at moderately high altitude, we prospectively studied 17 men with sickle cell trait and 25 men with normal hemoglobin. All subjects had resided at > or = 1609 m above sea level for at least 10 years. Resting pulmonary function and cardiopulmonary performance during exercise to exhaustion were evaluated. No statistically significant differences were observed between subjects with sickle cell trait and controls for any of the resting pulmonary function variables measured. All parameters of exercise performance were not statistically different between the groups. Increasing age was associated with a similar decrease in work capacity and oxygen consumption in both groups. Electrocardiogram findings were not statistically different between groups. We conclude that chronic exposure to moderately high altitude does not impair cardiopulmonary function in men with sickle cell trait.

Adult↗

PubMed1989

Subcortical cerebral infarctions in sickle cell trait.

At necropsy, two patients with sickle cell trait and progressive motor and visual deficits, lethargy and coma showed infarctions of the deep cerebral white matter and brain stem. The findings in these patients and another reported in the literature suggest that subcortical infarctions may be more common in sickle cell trait than has been recognised and should be suspected in any patient with sickle cell trait who presents with an unusual neurological illness.

Adult↗

PubMed1994

Internuclear ophthalmoplegia in sickle cell trait.

An 8-year-old boy presented with symptoms compatible with a right internuclear ophthalmoplegia. Magnetic resonance imaging showed a high-intensity signal on T2-weighted images at the level of the medial longitudinal fasciculus. Laboratory evaluation was positive only for sickle cell trait. Sickle cell trait is an uncommon cause for brainstem infarction.

Brain Stem↗

PubMed2026

Nephropathies Associated with Sickle Cell Trait and How to Study Them.

Sickle cell trait (SCT), which carries a single point mutation in the hemoglobin-β (HBB) gene, has long been considered a benign condition. However, epidemiological evidence challenges this assumption, revealing that individuals with SCT face an elevated risk of renal dysfunction. However, this field of study remains ill-defined as it has focused on sickle cell disease (SCD), where renal complications are severe. As SCT is more prevalent than SCD, consequences of nephropathies in this group translate into a substantial and largely unaddressed public health burden. Clinical data, primarily observational, implicate age and sex in the development of SCT-associated nephropathies. These manifestations span glomerular hyperfiltration, tubular damage, hematuria, renal papillary necrosis, renal medullary carcinoma, and progression to chronic kidney disease, all complications that cluster disproportionately in older male individuals. Despite this, the mechanistic basis of SCT nephropathy, the thresholds at which renal injury becomes clinically significant, and the optimal strategies for early identification and prevention remain inadequately defined. In vitro studies have primarily focused on SCD blood cell biology, with SCT receiving comparatively little attention. Humanized murine models (i.e., Berkeley and Townes) have recapitulated some SCT-associated renal phenotypes but need to be more fully characterized. This review aims to provide an overview of the biology of sickle cell trait nephropathies, the gaps in our knowledge, and the model systems we can use to fill those gaps.

Journal Article↗

PubMed1992

Splenic sequestration associated with sickle cell trait and hereditary spherocytosis.

Coexistence of sickle cell trait and hereditary spherocytosis (HS) is unusual, and only 16 cases have been reported in the literature. These patients have the same clinical and hematological features as individuals having HS alone. We report a serious complication, acute splenic sequestration crisis (ASSC), occurring in two patients with sickle cell trait and HS. One patient experienced four episodes of ASSC during an 11-year span, while the other had two episodes of this complication during a 4-year period. Red blood cell studies and membrane protein analysis confirmed the diagnosis of HS as a consequence of spectrin deficiency. Splenectomy resulted in marked clinical and hematological improvement in both patients. Histological examination of spleens following splenectomy confirmed that significant erythrostasis and sickling had indeed occurred. ASSC can occur in patients with coexistence of sickle cell trait and HS, and this potentially life-threatening complication should be considered in this condition.

Adolescent↗

PubMed2006

Does the pattern of repeated sprint ability differ between sickle cell trait carriers and healthy subjects.

Sickle cell trait (SCT) is a genetic abnormality affecting the synthesis of normal haemoglobin [Hb] and is the heterozygous form of sickle cell anaemia. The aim of the present study was to compare the ability to repeat maximal cycling sprints (RSA; repeated sprint ability) between SCT carriers (SCT group, n = 7) and a control group with normal haemoglobin [Hb] (n = 7). The two groups performed a 10-s maximal cycling sprint in order to determine the peak power output (P(peak10)). They then performed an RSA test that consisted of five 6-s maximal cycling sprints interspersed with 24 s of passive recovery. For each sprint, the peak power output (P(peak6)) and the work over the 6-s (W6) were calculated. The sum of each W6 developed during the test was considered to be the total work (W(tot)). The decrements over the repeated sprints for P(peak6) (P(6dec)) and W6 (W(6dec)) were also determined. We found no difference in P(peak10), W(tot) and W(6dec) between the two groups. However, the drop in P(peak6) and W6 during the RSA test appeared earlier in the SCT group and the decrease in P(peak6) over the RSA test was greater in the SCT group than in the control group (p < 0.05). In conclusion, we found that: 1) maximal anaerobic performance determined during a single sprint was not altered by SCT, but 2) repeated sprint ability was different in SCT carriers compared with sportsmen with normal Hb.

Adult↗

PubMed1982

Sickle cell trait: an update.

A review of the literature on sickle cell trait was completed by Sears in 1978. Since that time, several papers have been published concerning the possible health risks of sickle cell trait. Data presented from these studies show that there is no association with sickle cell trait and overall survival, overall mortality, overall morbidity, frequency and length of hospitalization, short-term survival of renal transplant recipient, and inheritance of glucose-6-phosphate dehydrogenase. Association with sickle cell trait is very likely in the following: splenic infarction at high altitudes (over 10,000 feet), in unpressurized airplane flight and mountain climbing, bacteriuria and pyelonephritis in pregnancy, hyposthenuria, hematuria, and delayed resolution of anterior chamber hyphema. Although these conditions have a statistical significant association with sickle cell trait, they occur quite infrequently. Thus, when they are observed, other causes should be sought before attributing them to sickle cell trait. Reduced mortality from Plasmodium falciparum infection also shows significant association with sickle cell trait.

Anemia, Sickle Cell↗

PubMed1989

Exercise and hypoxia increase sickling in venous blood from an exercising limb in individuals with sickle cell trait.

PURPOSE: The association between sickle cell trait (SCT) and complications related to exercise may be explained if exercise-induced sickling interferes with capillary blood flow and causes tissue ischemia and functional abnormalities. To test this hypothesis, we measured sickling and blood gas values in venous and arterial blood of an exercising limb in subjects with SCT and in controls. SUBJECTS AND METHODS: The study consisted of 15 subjects with hemoglobin AS (SCT group) and 15 subjects with hemoglobin AA (control group). Each performed two maximal arm crank exercise tests, one at 1,270 meters and one at simulated 4,000 meters. RESULTS: At 1,270 meters, axillary venous sickling increased significantly (p less than 0.05) from (mean +/- SD) 1.0 +/- 1.0% at rest to 2.3 +/- 2.6% during peak exercise. At simulated 4,000 meters, sickling increased significantly (p less than 0.001) from 1.5 +/- 1.2% to 8.5 +/- 7.1%. A wide range of sickling during peak exercise was observed (1% to 25%). One minute after exercise at simulated 4,000 meters, venous sickling remained elevated (7.2 +/- 7.8%) despite high levels of oxygen saturation. Arterial sickling (less than 1%) was present in only two subjects. There was no significant difference in oxygen consumption (29.4 +/- 3 versus 30.7 +/- 4 mL/kg/minute) between the subjects with SCT and the controls, nor was there a correlation between exercise performance and sickling (r less than 0.2). CONCLUSION: We conclude that exercise at 1,270 meters slightly, albeit significantly, increased sickling in blood from an exercising limb and that simulated 4,000 meters dramatically potentiated this effect. Sickling in the effluent blood of an exercising limb does not appear to measurably affect overall maximal arm crank exercise performance.

Adult↗

PubMed2004

[Retinopathy as a sickle-cell trait: myth or reality?].

INTRODUCTION: The retinopathy of sickle cell diseases is an ischemic retinopathy that occurs frequently in the major forms of HbSS and HbSC sickle cell diseases. The retinopathy of sickle trait HbAS has not been described extensively. PATIENTS AND METHODS: The aim of this study was to describe the retinal characteristics and thus gain better knowledge of sickle trait HbAS retinopathy. Seventy HbAS patients had a complete ocular examination including fluorescein angiography. RESULTS: Seventy percent of the patients had retinal lesions, with 49.3% non-vasoproliferative lesions, 22.7% prevasoproliferative lesions and 2.7% neovascular lesions. DISCUSSION AND CONCLUSION: Retinopathy is associated with the HbAS sickle cell trait, but it is less serious than in the major forms of sickle cell syndrome.

Adolescent↗

PubMed2005

[Physical performance and thermoregulatory study of subjects with sickle cell trait during a sub-maximal exercise].

The sickle cell trait is a genetic abnormality of red blood cells. It is due to the mutation of a parental gene, which rest Its to the substitution of glutamic acid by valin on beta globin chain of haemoglobin. The possibility for sickle cell trait carriers (SCT) to present any disturbance during predominantly anaerobic and aerobic exercises is unclear. Ten (10) subjects with sickle cell trait and 10 subjects control were studied during exercise test on cycloergometer. They were all students of the National Institute of Popular Education and Sport of Dakar. The mean of environmental temperature was 26 degrees C and humidity was 60 to 80%. After haematological analysis, a submaximal muscular exercise for one hour with 75% of maximal heart rate was done. We have determined heart rate, blood pressure, rectal and skin temperature during exercise. Haematological parameters shown any significant difference between the two groups. No significant difference was found in cardiocirculatory variables during maximal exercise in cycloergometer between control group and sickle cell trait group. The two groups have done submaximal exercise during 1 hour without particular difficulty. We have not observed a significant difference between the two groups in cardiovascular variables, rectal and skin temperature during exercise, and after 3 minutes of rest. These results show that subjects with SCT have physical capacity comparable with control subjects during a sub maximal exercise for 1 hour. We can assure that subjects with SCT in our country may participate in sports competition, as well as normal subjects (HbAA).

Blood Pressure↗

PubMed1976

Medical management of refractory hematuria in sickle-cell trait.

Hematuria secondary to sickle-cell trait has on occasion proved refractory to medical management. We have adopted a new six-drug regimen to deal with this difficult problem. Herein is reported our experience with this protocol in 2 patients. Our results have been excellent, with hematuria clearing within twenty-four hours. The drug regimen is used in an attempt to alter the conditions that are favorable for sickling in the renal medulla.

Acetazolamide↗

PubMed1983

Sickle cell trait in pregnancy.

In pregnancy, sickle cell trait is associated with an increased incidence of urinary tract infection. Hemoglobin S levels vary from 25% to 44%. Patients with lower hemoglobin S levels are less likely to have urinary tract infections than patients with higher levels of hemoglobin S.

Adolescent↗

PubMed1996

Sudden exertional death in a soldier with sickle cell trait.

Most family physicians regard sickle cell trait (SCT) as a benign condition. But in special circumstances SCT can have deadly consequences. SCT affects 8% of the black population. Most of the cases of sudden exertional death (SED) in those with SCT have occurred during military basic training. A retrospective review of all soldiers in basic training found that those with SCT had a 40-fold increased risk of SED. This paper discusses an individual case of SED that occurred at Fort Sill, Oklahoma. A literature review makes comparisons to our index case. The current Army Medical Corps recommendations for prevention of SED as well as the current military SCT screening policy will be discussed. Prospective studies are needed to evaluate the efficacy of the currently recommended preventative guidelines as well as to more fully evaluate the potential for SCT to cause significant morbidity and mortality during military basic training.

Adult↗

PubMed1998

[Influence of the sickle cell trait heterozygote on energy abilities].

The sickle cell trait (SCT) is a genetic abnormality of the red blood cell which mainly affects people of African descent. It is due to the mutation of only one parental gene (one glutamic acid of the chain beta of the globin is substituted by one valin). The prevalence of SCT in the black US population is within the range of 8-9%. It is increasing in Europe and in Africa where it may reach up to 40% in some regions. The rate of prevalence of SCT in athletic populations was found to be similar to that of the general sedentary population in west African countries. SCT is usually asymptomatic. However, SCT has been associated with a higher risk of sudden death during exercise. In fact, the substitution of one amino-acid modifies the properties of haemoglobin and produces physiological disorders such as sickling, less solubility of the deoxidized form and the reduction of affinity for oxygen. The sickling phenomenon (formation of sickle cells) mainly occurs in some conditions related to the practise of sport (intense and/or prolonged exercise, exercise in hypoxic conditions, exercise in heat conditions). These sickled red blood cells reduce the speed of capillary flow or obstruct the blood vessels which, because of the lack of oxygen, become altered. The physical ability of sickle cell trait carriers (HbAS) who practise sport should be different from the physical ability of subjects with normal haemoglobin (HbAA) because of: 1) potential risks due to their haemoglobinopathy and 2) the eventual modification of their performance ability. These two aspects have caused controversies among many researchers particularly in line with their investigation methods. Nevertheless, the following results seem to be established: 1) the ability to perform sprint exercises is not altered in the HbAS subjects. Their performances in these events are similar to those of HbAA subjects; 2) The ability of HbAS subjects to perform intense and prolonged exercise is decreased. Our former results have shown that prolonged aerobic efforts in hypobaric hypoxic conditions may be associated with a deleterious effect on the performance of HbAS subjects. The damaging consequences on their performance in these conditions could be due to tissue oxygen delivery limitations.

Energy Metabolism↗

PubMed2006

Outcome of pregnancy in a population of Nigerian women with sickle cell trait.

Although variable clinicopathological entities have been documented in sickle cell trait in pregnancy, such information is absent in this environment. This study therefore was aimed at examining the outcome of pregnancy in a population of Nigerian women with sickle cell trait. A prospective analytical study was carried at Ile-Ife, Nigeria comparing morbidities and mortalities between 210 pregnant women with sickle cell trait and 210 women with HbAA. Data were processed using SPSS 11.0 and PEPI packages, and the p value was set at =0.05. There were no significant differences between mothers with sickle cell trait and HbAA in terms of sociodemographic characteristics, the course of labour, deliveries and morbidity patterns. However, mothers with sickle cell trait had significantly fewer attacks of malaria in pregnancy (25.7% compared with 34.8%) and faster recovery of their newborn from birth asphyxia at 1 min (0.9% compared with 4.9%). Sickle cell trait may confer greater resistance to malaria in pregnancy and carries no extra risk to the outcome of pregnancy.

Adult↗

PubMed1983

Diaphyseal bone infarctions in a patient with sickle cell trait.

Bone and joint abnormalities occur frequently in sickle cell anemia but are rare in sickle cell trait. Long bone diaphyseal infarctions are distinctly unusual in sickle cell trait. We describe a patient with AS hemoglobin and symptomatic bone infarctions in the diaphyses and metadiaphyses of the long bones of the lower extremities and in the calcaneus. In addition, this patient manifested noninflammatory synovial effusions of the knee. The bone and joint manifestations of sickle cell trait are reviewed in the context of this case.

Adult↗