Seeing haemoglobin SC: Challenging the misperceptions.

Historically understudied and regarded as a mild type of sickle cell disease, HbSC can be associated with significant, progressive complications. Prospective studies are urgently needed to address treatment gaps for HbSC disease. Commentary on: Nelson et al. The clinical spectrum of HbSC sickle cell disease-not a benign condition. Br J Haematol 2024;205:653-663.

The clinical spectrum of HbSC sickle cell disease-not a benign condition.

Sickle cell disease (SCD) includes a group of heterogenous disorders that result in significant morbidities. HbSS is the most common type of SCD and HbSC is the second most common type of SCD. The prevalence of HbSC disease in the United States and United Kingdom is ~1 in 7174 births and 1 in 6174 births respectively. Despite its frequency, however, HbSC disease has been insufficiently studied and was historically categorized as a more 'mild' form of SCD. We conducted this study of HbSC disease as part of the NHLBI funded Sickle Cell Disease Implementation Consortium (SCDIC). The SCDIC registry included 2282 individuals with SCD, ages 15-45 years of whom 502 (22%) had HbSC disease. Compared with people with sickle cell anaemia (SCA), the study found that people with HbSC disease had a higher frequency of splenomegaly (n (%) = 169 (33.7) vs. 392 (22.1)) and retinopathy (n (%) = 116 (23.1) vs. 189 (10.6)). A Many people with HbSC also had avascular necrosis (n (%) = 112 (22.3)), pulmonary embolism (n (%) = 43 (8.6)) and acute chest syndrome (n (%) = 228 (45.4)) demonstrating significant disease severity. HbSC disease is more clinically severe than was previously recognized and deserves additional evaluation and targeted treatments.

Systemic medications for sickle cell disease and potential applications for sickle cell retinopathy.

PURPOSE OF REVIEW: To review the literature evaluating systemic medications for treatment of sickle cell disease (SCD) and their applications for sickle cell retinopathy. RECENT FINDINGS: Prior studies have demonstrated the efficacy of traditional systemic therapies in reducing the risk of development of sickle cell retinopathy. Since 2017, several new and promising disease-modifying therapies for sickle cell disease have been approved for clinical use, including the first genetic therapies such as exagamglogene autotemcel (exa-cel) and lovotibeglogene autotemcel (lovo-cel). These treatments have shown promising results for systemic management but are not widely utilized due to limited access and high cost. The efficacy of these therapies for the prevention of sickle cell retinopathy remains unknown and opens the door to new avenues for research. Furthermore, the role of systemic therapy for the management of hemoglobin SC (HbSC) disease, which has milder systemic effects but higher likelihood of causing retinopathy, remains poorly understood. SUMMARY: Hydroxyurea has been a mainstay of systemic management of SCD with prior work suggesting its ability to reduce the likelihood of developing retinopathy. There are several new and potentially curative systemic therapies for SCD, though their role in retinopathy prevention and management has not been studied extensively. Future studies are necessary to understand the implications of these emerging therapies for sickle cell retinopathy.

Bilateral tractional retinal detachment in hemoglobin SC disease patient / Descolamento tracional de retina bilateral em hemoglobinopatia S-C

ABSTRACT A 36-year-old black male presented with a progressive loss of visual acuity in both eyes for 7 years. He had a history of tractional retinal detachment in the right eye and vitreous hemorrhage followed by retinal detachment in the left eye. He denied any systemic illness, trauma, or drug abuse. After clinical investigation, he was diagnosed with SC hemoglobinopathy and proliferative sickle cell retinopathy stage V in both eyes.

RESUMO Paciente do sexo masculino, 36 anos, negro, apresentou baixa acuidade visual progressiva em ambos os olhos por 7 anos. Possuía antecedentes de descolamento tracional de retina no olho direito e hemorragia vítrea, seguida de descolamento de retina no olho esquerdo. Negava doenças sistêmicas, trauma ou abuso de drogas. Após investigação clínica, foi diagnosticado com hemoglobinopatia S-C e retinopatia falciforme proliferativa estágio V em ambos os olhos.

Metabolic signatures of cardiorenal dysfunction in plasma from sickle cell patients as a function of therapeutic transfusion and hydroxyurea treatment.

Metabolomics studies in sickle cell disease (SCD) have been so far limited to tens of samples, owing to technical and experimental limitations. To overcome these limitations, we performed plasma metabolomics analyses on 596 samples from patients with SCD enrolled in the WALK-PHaSST study (clinicaltrials gov. Identifier: NCT00492531). Clinical covariates informed the biological interpretation of metabolomics data, including genotypes (hemoglobin [Hb] SS, hemoglobin SC), history of recent transfusion (HbA%), response to hydroxyurea treatment (fetal Hb%). We investigated metabolic correlates to the degree of intravascular hemolysis, cardiorenal function, as determined by tricuspid regurgitation velocity (TRV), estimated glomerular filtration rate (eGFR), and overall hazard ratio (unadjusted or adjusted by age). Recent transfusion events or hydroxyurea treatment were associated with elevation in plasma-free fatty acids and decreases in acyl-carnitines, urate, kynurenine, indoles, carboxylic acids, and glycine- or taurine-conjugated bile acids. High levels of these metabolites, along with low levels of plasma S1P and L-arginine were identified as top markers of hemolysis, cardiorenal function (TRV, eGFR), and overall hazard ratio. We thus uploaded all omics and clinical data on a novel online portal that we used to identify a potential mechanism of dysregulated red cell S1P synthesis and export as a contributor to the more severe clinical manifestations in patients with the SS genotype compared to SC. In conclusion, plasma metabolic signatures - including low S1P, arginine and elevated kynurenine, acyl-carnitines and bile acids - are associated with clinical manifestation and therapeutic efficacy in SCD patients, suggesting new avenues for metabolic interventions in this patient population.

Epidemiological and clinical features, therapeutic strategies and outcomes in patients with hyperhaemolysis: A systematic review.

Hyperhaemolysis syndrome (HHS), a severe form of delayed haemolytic transfusion reaction most commonly described in patients with sickle cell disease (SCD), involves destruction of both donor and recipient red blood cells (RBCs). As the epidemiology and underlying pathophysiology have yet to be definitively elucidated, recognition can be challenging. We systematically reviewed PubMed and EMBASE to identify all cases of post-transfusion hyperhaemolysis and characterized the epidemiological, clinical and immunohaematological characteristics and treatments of HHS. We identified 51 patients (33 females and 18 males), including 31 patients with SCD (HbSS, HbSC and HbS/ß-thalassaemia). The median haemoglobin nadir (3.9 g/dL) occurred a median of 10 days post-transfusion. 32.6% and 45.7% of patients had a negative indirect anti-globulin test and a negative direct anti-globulin test, respectively. The most common therapies included corticosteroids and intravenous immune globulin. 66.0% of patients received ≥1 supportive transfusion, which was associated with a longer median hospital stay/time to recovery (23 days vs. 15 days; p = 0.015) compared to no supportive transfusion. These findings illustrate that HHS that often results in marked anaemia 10 days post-transfusion is not restricted to patients with haemoglobinopathies, and additional transfused RBCs may be associated with a longer time-to-recovery.

Characterising the prevalence of overweight and obese status among adults with sickle cell disease.

Individuals with sickle cell disease (SCD) have historically been considered underweight. Despite increasing body mass index (BMI) in the general population, the prevalence of overweight and obese status remains unclear in the adult SCD population. Our primary aim was to determine the prevalence of overweight and obese status and to identify associations between BMI, demographic, and clinical characteristics. We conducted an analysis of abstracted electronic health record data and patient-reported outcomes from the Sickle Cell Disease Implementation Consortium registry; individuals aged 20-45 years were included. The median (interquartile range) BMI for the 1664 adults in this analysis was 23.9 (21.1-28) kg/m2 . In this cohort, 42.9% had a BMI of >25 kg/m2 (Centers for Disease Control and Prevention definition of overweight/obese). In multivariable analysis, higher odds of being overweight or obese were associated with female gender, older age, college education, private insurance, and hypertension diagnosis. Higher odds of a BMI of >25 kg/m2 were observed in individuals with HbSC or HbSß+ thalassaemia regardless of hydroxycarbamide (hydroxyurea) exposure (odds ratio [OR] 3.4, p < 0.0001) and HbSS or HbSß0 thalassaemia exposed to hydroxycarbamide (OR 1.6, p = 0.0003) compared to those with HbSS or HbSß0 thalassaemia with no hydroxycarbamide exposure. These data highlight the importance of early identification, prevention, and intervention for increasing BMI to reduce obesity-related complications that may impact SCD-related complications.

Main Complications during Pregnancy and Recommendations for Adequate Antenatal Care in Sickle Cell Disease: A Literature Review.

Sickle cell disease (SCD) is the most common monogenic disease worldwide, with a variable prevalence in each continent. A single nucleotide substitution leads to an amino-acid change in the ß-globin chain, altering the normal structure ofhemoglobin, which is then called hemoglobin S inherited in homozygosity (HbSS) or double heterozygosity (HbSC, HbSß), and leads to chronic hemolysis, vaso-occlusion, inflammation, and endothelium activation. Pregnant women with SCD are at a higher risk of developing maternal and perinatal complications. We performed a narrative review of the literature considering SCD and pregnancy, the main clinical and obstetrical complications, the specific antenatal care, and the follow-up for maternal and fetal surveillance. Pregnant women with SCD are at a higher risk of developing clinical and obstetric complications such as pain episodes, pulmonary complications, infections, thromboembolic events, preeclampsia, and maternal death. Their newborns are also at an increased risk of developing neonatal complications: fetal growth restriction, preterm birth, stillbirth. Severe complications can occur in patients of any genotype. We concluded that SCD is a high-risk condition that increases maternal and perinatal morbidity and mortality. A multidisciplinary approach during pregnancy and the postpartum period is key to adequately diagnose and treat complications.

Doença falciforme (DF) é a condição genética mais comum no mundo, com uma prevalência variável nos continentes. A substituição de um nucleotídeo muda um aminoácido na cadeia da ß globina, e altera a estrutura normal da hemoglobina, que é então chamada de hemoglobina S, e pode ser herdada em homozigose (HbSS) ou heterozigose (HbSC, HbSß), e leva a hemólise crônica, vaso-oclusão, inflamação, e ativação endotelial. Realizou-se uma revisão narrativa da literatura considerando doença falciforme e gestação, as complicações clínicas e obstétricas, o cuidado antenatal específico, e o seguimento para monitoramento materno e fetal. Gestantes com DF têm maior risco de desenvolver complicações clínicas e obstétricas, como crises dolorosas, complicações pulmonares, infecções, eventos tromboembólicos, pré-eclâmpsia, e morte materna. E seus recém-nascidos correm maior risco de desenvovler complicações neonatais: restrição de crescimento fetal, prematuridade e óbito fetal/neonatal. Complicações graves podem ocorrer em qualquer genótipo da doença. Concluiu-se que DF é uma condição de alto risco que aumenta a morbimortalidade materna e perinatal. Um seguimento com abordagem multidisciplinar na gestação e puerpério é fundamental para o diagnóstico e o tratamento das complicações.

Unusually High Prevalence of Stroke and Cerebral Vasculopathy in Hemoglobin SC Disease: A Retrospective Single Institution Study.

INTRODUCTION: Unlike homozygous hemoglobin SS (HbSS) disease, stroke is a rare complication in hemoglobin SC (HbSC) disease. However, recent studies have demonstrated a high prevalence of silent stroke in HbSC disease. The factors associated with stroke and cerebral vasculopathy in the HbSC population are unknown. METHODS: We conducted a retrospective study of all patients with sickle cell disease treated at the University of Missouri, Columbia, over an 18-year period (2000-2018). The goal of the study was to characterize the silent, overt stroke, and cerebral vasculopathy in HbSC patients and compare them to patients with HbSS and HbS/ß thalassemia1 (thal) in this cohort. We also analyzed the laboratory and clinical factors associated with stroke and cerebral vasculopathy in the HbSC population. RESULTS: Of the 34 HbSC individuals, we found that the overall prevalence of stroke and cerebral vasculopathy was 17.7%. Only females had evidence of stroke or cerebral vasculopathy in our HbSC cohort (33.3%, p = 0.019). Time-averaged means of maximum velocities were lower in the HbSC group than the HbSS group and did not correlate with stroke outcome. Among HbSC individuals, those with stroke and cerebral vasculopathy had a marginally higher serum creatinine than those without these complications (0.77 mg/dL vs. 0.88 mg/dL, p = 0.08). Stroke outcome was associated with recurrent vaso-occlusive pain crises (Rec VOCs) (75 vs. 25%, p = 0.003) in HbSC patients. The predominant cerebrovascular lesions in HbSC included microhemorrhages and leukoencephalopathy. CONCLUSION: There is a distinct subset of individuals with HbSC who developed overt, silent stroke, and cerebral vasculopathy. A female predominance and association with Rec VOCs were identified in our cohort; however, larger clinical trials are needed to identify and confirm specific clinical and laboratory markers associated with stroke and vasculopathy in HbSC disease.

Neurocognitive functioning in preschool children with sickle cell disease.

BACKGROUND: Children with sickle cell disease (SCD) experience neurodevelopmental delays; however, there is limited research with preschool-age children. This study examined neurocognitive risk and protective factors in preschoolers with SCD. PROCEDURE: Sixty-two patients with SCD (60% HbSS/HbSß0 -thalassemia; 40% HbSC/HbSß+ -thalassemia) between the ages of 3 and 6 years (mean = 4.77 years) received a neuropsychological evaluation as routine systematic surveillance. Patients were not selected for disease severity, prior central nervous system findings, or existing cognitive concerns. Thirty-four patients (82% HbSS/HbSß0 -thalassemia) were prescribed hydroxyurea (HU) at the time of their neuropsychological evaluation. On average, these patients had been prescribed HU at 2.15 (standard deviation = 1.45) years of age. The average dose was 28.8 mg/kg/day. Besides genotype, there were no group differences in medical or demographic factors based on HU treatment status. RESULTS: Patients with HbSS/HbSß0 -thalassemia scored below normative expectations on measures of intelligence, verbal comprehension, and school readiness (false discovery rate-adjusted p-value [pFDR ] < .05). Age, sickle genotype, and HU treatment exposure were not associated with measured neurocognitive outcomes (pFDR  > .05). Greater social vulnerability at the community level was associated with poorer performance on measures of intellectual functioning, verbal comprehension, visuomotor control, and school readiness, as well as parent report of executive dysfunction (pFDR  < .05). Greater household socioeconomic status was positively associated with academic readiness. CONCLUSIONS: Preschoolers with severe SCD (HbSS/HbSß0 -thalassemia) perform below age expectations on measures of intelligence and academic readiness. Sociodemographic factors were stronger drivers of neurocognitive performance than disease severity or disease-modifying treatment. Neurodevelopmental interventions targeting the home and broader community environment are needed.

Epstein-Barr virus-induced sickle hepatopathy.

Sickle hepatopathy comprises a spectrum of disorders that vary in severity. Intravascular sickling and sinusoidal occlusion are the principal drivers of sickle hepatopathy, but infection or autoimmunity can act as triggers. We describe two cases of acute sickle hepatopathy initiated by primary Epstein-Barr virus (EBV) infection, a previously unreported association. The first case entailed a 14-year-old girl with hemoglobin SC (HbSC) disease who developed hepatic sequestration crisis that responded to a simple transfusion of erythrocytes. The second case was that of a 16-year-old boy with HbSC disease who experienced life-threatening intrahepatic cholestasis with multiorgan failure.

Prophylactic antibiotics for preventing pneumococcal infection in children with sickle cell disease.

BACKGROUND: Sickle cell disease (SCD) is a group of inherited disorders that result in haemoglobin abnormalities and other complications. Injury to the spleen, among other factors, contribute to persons with SCD being particularly susceptible to infection. Infants and very young children are especially vulnerable. The 'Co-operative Study of Sickle Cell Disease' observed an incidence rate for pneumococcal septicaemia of 10 per 100 person-years in children under the age of three years. Vaccines, including customary pneumococcal vaccines, may be of limited use in this age group. Therefore, prophylactic penicillin regimens may be advisable for this population. This is an update of a Cochrane Review which was first published in 2002, and previously updated, most recently in 2017.  OBJECTIVES: To compare the effects of antibiotic prophylaxis against pneumococcus in children with SCD receiving antibiotic prophylaxis compared to those without in relation to: 1. incidence of Streptococcus pneumoniae infection; 2. mortality (as reported in the included studies); 3. drug-related adverse events (as reported in the included studies) to the individual and the community; 4. the impact of discontinuing at various ages on incidence of infection and mortality. SEARCH METHODS: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register, which is comprised of references identified from comprehensive electronic database searches and also two clinical trials registries: ClinicalTrials.gov and the WHO International Registry Platform (not in 2020 given access issues relating to Covid-19 pandemic). Additionally, we carried out hand searching of relevant journals and abstract books of conference proceedings. Date of the most recent search: 25 January 2021. SELECTION CRITERIA: All randomised or quasi-randomised controlled trials comparing prophylactic antibiotics to prevent pneumococcal infection in children with SCD with placebo, no treatment or a comparator drug. DATA COLLECTION AND ANALYSIS: The standard methodological procedures expected by Cochrane were used. Both authors independently extracted data and assessed trial quality. The authors used the GRADE criteria to assess the certainty of the evidence. MAIN RESULTS: Six trials were identified by the searches, of which three trials were eligible for inclusion. A total of 880 children, who were between three months to five years of age at randomization were included. The included studies were conducted in centres in the USA and in Kingston, Jamaica. In trials that investigated initiation of penicillin on risk of pneumococcal infection, the odds ratio was 0.37 (95% confidence interval 0.16 to 0.86) (two trials, 457 children) (low-certainty evidence), while for withdrawal the odds ratio was 0.49 (95% confidence interval 0.09 to 2.71) (one trial, 400 children) (low-certainty evidence). Adverse drug effects were rare and minor. Rates of pneumococcal infection were found to be relatively low in children over the age of five years. Overall, the certainty of the evidence for all outcomes was judged to be low. The results from the risk of bias assessment undertaken identified two domains in which the risk of bias was considered to be high, these were incomplete outcome data (attrition bias) (two trials) and allocation concealment (selection bias) (one trial). Domains considered to have a low risk of bias for all three trials were selective reporting (reporting bias) and blinding (performance and detection bias). AUTHORS' CONCLUSIONS: The evidence examined was determined to be of low certainty and suggests that prophylactic penicillin significantly reduces risk of pneumococcal infection in children with homozygous SCD, and is associated with minimal adverse reactions. Further research may help to determine the ideal age to safely withdraw penicillin.

Another 'BEE'? - Brain-Eye-Ear (BEE) Disease Secondary to HbSC Disease Masquerading as Multiple Sclerosis.

Recurrent episodes of neurological dysfunction and white matter lesions in a young adult raise suspicion for multiple sclerosis (MS). However, occlusive retinopathy, hearing loss and absence of CSF oligoclonal bands are atypical for MS and should make the clinician consider an alternative diagnosis. We describe a man with hearing loss, visual signs and symptoms, and an accumulating burden of brain lesions, who was treated for a clinical diagnosis of MS for nearly two decades. Genetic testing revealed a unifying diagnosis.

Sequential development of human herpes virus 8-positive diffuse large B-cell lymphoma and chronic myelomonocytic leukemia in a 59 year old female patient with hemoglobin SC disease.

Hematolymphoid neoplasms, including lymphoma and myeloid neoplasms, can occur in patients with sickle cell disease (SCD) or equivalent hemoglobinopathy, but an underlying connection between the two conditions has yet to be fully determined. Herein, we report a unique case of sequential development of two separate hematolymphoid neoplasms, human herpes virus 8 (HHV8)-positive diffuse large B-cell lymphoma (DLBCL) and chronic myelomonocytic leukemia, in a 59 year-old African American female with hemoglobin SC disease. While etiology of immunodeficiency is unknown, the potential causes include hydroxyurea therapy, disease related immunomodulation, chronic inflammation, and relatively old age. The leukemia cells demonstrated profound trilineage dysplasia and harbored complex cytogenetic abnormalities with loss of chromosome 5q and 7q, which are often observed in therapy-related myeloid neoplasms. Besides the potential causes listed above, we propose that myeloid leukemia in this setting may result from genomic changes due to excessive hematopoietic replication triggered by a hemolysis-induced cytokine storm. While myeloid neoplasms in the setting of SCD seems to herald a dismal clinical outcome per the literature, the HHV8-positive DLBCL in our case was apparently indolent, opposing the current perception of its clinical outcome.