[Disease modifying treatments for sickle cell disease]

DISEASE MODIFYING TREATMENTS FOR SICKLE CELL DISEASE. The two most widely available disease-modifying therapies, hydroxycarbamide and long-term redblood cells transfusions, are mostly introduced after the occurrence of complications. Hydroxycarbamide is mainly prescribed for the prevention of recurrent vaso-occlusive events (vaso-occlusive crisis and acute chest syndrome). Hydroxycarbamide efficacy and myelosuppressive effects are dependent on dose (usually 15 to 35 mg/kg/d) and patient compliance. Long-term transfusions are used for cerebral and end-organ damage protection or in second line after hydroxycarbamide for the prevention of recurrent vaso-occlusive events. The risks of each treatment should be weighed against the long-term risks and morbidity of the disease.

[Management of acute complications of sickle cell disease]

MANAGEMENT OF ACUTE COMPLICATIONS OF SICKLE CELL DISEASE. Acute complications are the most frequent causes of hospitalization and morbidity in patients with sickle cell disease. Vaso-occlusive crisis are responsible of more than 90% of hospitalization, but numerous acute complications can affect multiples organ or function, that may be life-threatening. Thus, a single reason for hospitalization may include many complications such as worsening of an anemia, vascular disease (stroke, thrombosis, priapism), acute chest syndrome, liver or spleen sequestration. Evaluation of acute complications includes the understanding of chronic complications, particularities related to patient's age, the search for a triggering factor and a differential diagnosis. Analgesia and venous access difficulties, post transfusion immunization, medical history of the patient can make the management of acute complication particularly complex.

[Therapeutic approaches in sickle cell disease]

THERAPEUTIC APPROACHES IN SICKLE CELL DISEASE. Sickle cell disease, the most common genetic disease in France, is still burdened with morbidity and early mortality before the age of 50. When the first-line treatment, hydroxyurea, is insufficient or in the case of organic damage(s) (in particular cerebral vasculopathy), a therapeutic intensification must be considered. New molecules are now available, such as voxelotor and crizanlizumab, but only hematopoietic stem cell (HSC) transplantation can cure the disease. Allogeneic HSC transplantation during childhood with a sibling donor is the reference but it is now possible to perform this procedure in adults with a reduced pre-transplant conditioning. Gene therapy, which consists of an autograft of genetically modified HSCs, has obtained promising results but has not yet demonstrated a complete cure of the disease (protocols underway). The toxicity of myeloablative conditioning (used in pediatrics or for gene therapy), particularly the sterility induced, and the risk of graft-versushost disease (for allogeneic transplantation) are limiting factors of these treatments.

[Epidemiology of sickle cell disease in France and in the world]

EPIDEMIOLOGY OF SICKLE CELL DISEASE IN FRANCE AND IN THE WORLD. In a few decades, sickle cell disease has become the leading rare disease in France, with nearly 30,000 patients. It is the country in Europe where the most patients live. For historical reasons of immigration, half of these French patients live in the Paris area. The number of births of affected children increases every year, which explains the recurrent and increasing hospitalizations for vaso-occlusive crises, impacting the care system. Sub-Saharan African countries, along with India, are the countries most affected by the disease with an incidence of up to 1% of births. While infant mortality has become rare in industrialized countries, it is major in Africa where more than half of the children will not reach the age of 10.

Mortality Rates and autopsy findings in fat embolism syndrome complicating sickle cell disease

Fat embolism syndrome is a rare but underdiagnosed complication of sickle cell disease associated with high morbidity and mortality. It affects predominantly patients with a previously mild course of their illness and those of non-SS genotypes while there is possibly an association with infection with human parvovirus B19 (HPV B19). Here, we present the mortality rates and autopsy findings of all reported cases to date. A systematic review has revealed 99 published cases in the world literature with a mortality rate of 46%. Mortality varied greatly according to the time of reported cases with no survivors in the 1940s, 1950s or 1960s and no deaths since 2020. 35% of cases had previously undiagnosed sickle cell disease and the latter was only identified at autopsy after developing fat embolism with a fatal outcome. 20% of cases reported after 1986 tested positive for HPV B19 with an associated mortality of 63% whereas in cases that have not documented HPV B19 infection the mortality was 32%. The organs most often staining positive for fat were the kidneys, lungs, brain and heart whereas ectopic haematopoietic tissue was found in 45% of the examined lung specimens.

Patient perception of voxelotor treatment benefit in sickle cell disease

Patients with sickle cell disease (SCD) experience a range of clinical symptoms, including acute and chronic pain, fatigue, and respiratory problems, as well as chronic organ complications that can lead to disability and accelerated mortality. Voxelotor is a first-in-class therapy that targets sickle hemoglobin polymerization, the root cause of SCD. It is approved by the US Food and Drug Administration for treatment of SCD in patients aged 4 years and older and in the European Union and United Arab Emirates for the treatment of SCD in patients aged 12 years and older. Here, we report the single-center experience of both clinician-determined and patient-reported benefits of voxelotor in 27 consecutive patients treated for at least 8 weeks. Clinical Global Impression of Change and Patient Global Impression of Change rating scales were used to capture clinicians’ and patients’ perceptions of change in overall patient health-related quality-of-life with voxelotor treatment. Laboratory data were also collected to assess clinical response to treatment. As observed in previous clinical studies, hemoglobin concentrations and markers of hemolysis were improved in patients treated with voxelotor. Most patients reported marked improvement in disease symptoms, which correlated well with the clinicians’ assessments. Although limited by the retrospective open-label study design, these findings suggest that voxelotor use has a positive impact on outcomes in patients with SCD.

Non-S Sickling Hemoglobin Variants: Historical, Genetic, Diagnostic, and Clinical Perspectives

Apart from hemoglobin-S (HbS), there are other Hb variants (non-S sickling Hb variants) that cause sickle cell disease. However, the profiles of these non-S sickling Hb variants have neither been collated nor harmonized. A literature search revealed 14 non-S sickling Hb variants (HbC-Harlem, HbC-Ziguinchor, HbS-Travis, HbS-Antilles, HbS-Providence, HbS-Oman, HbS-Cameroon, HbS-South End, Hb Jamaica Plain, HbC-Ndjamena, HbS-Clichy, HbS-San Martin, HbS-Wake, and HbS-São Paulo). Generally, the non-S sickling Hb variants are double mutants with the HbS mutation (GAG>GTG: βGlu6Val) and additional β-chain mutations. Consequently, non-S sickling Hb variants give positive solubility and sickling tests, but they differ from HbS with respect to stability, oxygen affinity, and electro-chromatographic characteristics. Similarities and discrepancies between HbS and non-S sickling Hb variants create diagnostic pitfalls that can only be resolved by elaborate electro-chromatographic and/or genetic tests. It is therefore imperative that tropical hematologists should have a thorough understanding of these atypical sickling Hb variants. Collated and harmonized appraisal of the non-S sickling Hb variants have not been previously undertaken. Hence, this paper aims to provide a comprehensive but concise historical, genetic, comparative, diagnostic, and clinical overview of non-S sickling Hb variants. The elaborate techniques often required for precise diagnosis of non-S sickling Hb variants are regrettably not readily available in low resource tropical countries, which paradoxically carry the heaviest burden of sickling disorders. We strongly recommend that tropical countries should upgrade their diagnostic laboratory facilities to avoid misdiagnosis of these atypical Hb mutants.

Nutritional and Hematological Status of Sudanese Women of Childbearing Age with Steady-state Sickle Cell Anemia

OBJECTIVES

We sought to investigate the nutritional and hematological status of Sudanese women of childbearing age with sickle cell anemia (SCA). Anthropometry and hematology were used to assess nutritional status and health and disease conditions, respectively.

METHODS

Women with steady-state (HbSS, n = 39; age = 19.0±2.7) and without (HbAA, n = 36; age, 19.8±2.7) SCA were recruited during a routine visit to the Hematology Clinic, Ibn-Auf Teaching Hospital, Khartoum, Sudan.

RESULTS

The two groups of women lived in similar environmental conditions and ate similar diets three times a day. However, despite taking regular meals, the women with sickle anemia were thinner and lighter (p < 0.001) and shorter (p = 0.002) compared with those who do not have the disease. Also, they had higher levels of mean corpuscular hemoglobin (Hb) concentration and white cell count (p < 0.001), mean corpuscular volume (p = 0.003), and platelet (p = 0.002) and lower packed cell volume and Hb (p < 0.001). There was no difference in levels of anthropometric and hematological variables between the hydroxyurea treated and untreated SCA patients (p > 0.050).

CONCLUSIONS

The low anthropometric (height, weight, and body mass index) and abnormal hematological values in the women with SCA in steady-state reflect sustained nutritional insults inflected by the disease and poverty. Tailored nutritional counseling/advice must be an integral part of managing patients with SCA. Such advice is particularly vital for women of childbearing age because of the adverse effects of prepregnancy nutritional deficiency on outcomes.

Respiratory Viral Infections in Sickle Cell Anemia: Special Emphasis on H1N1 Co-infection

Objectives

Patients with sickle cell anemia (SCA) are immunocompromised and at an increased risk of developing infections. Our aim was to establish the clinical, laboratory, and radiological manifestations of respiratory viral infections in SCA at Sultan Qaboos University Hospital (SQUH), Oman and assess its impact on disease morbidity and mortality, with special emphasis on H1N1.

Methods

We undertook a retrospective study in SCA patients with respiratory viral infections following up at the hematology department at SQUH. We collected demographic data and clinical, radiological, and laboratory parameters.

Results

In 84 SCA patients with 109 admission episodes for vaso-occlusive crisis (VOC), molecular diagnostic techniques confirmed 125 respiratory viral infections. Rhinovirus was the most prevalent infection (35.8%), whereas H1N1 virus infection was seen only in 10.1%. Laboratory investigations revealed a significant fall in mean hemoglobin levels, mean white blood cell, and platelet counts from baseline, whereas there was a significant rise in the mean lymphocyte and retic count, serum lactate dehydrogenase, and C-reactive protein levels during infective episodes (p < 0.050, Wilcoxon signed rank test). One-third (32.1%) of the VOC episodes progressed to acute chest syndrome (ACS), but in the H1N1 cohort, only two episodes of ACS was seen (18.2%).

Conclusions

Rhinovirus was the commonest respiratory virus infections in SCA patients, whereas parainfluenza 3 was associated with a significant adverse outcome. H1N1 was associated with a mild course. ACS was seen in approximately one-third of this group of patients.

Occurrence of Multidrug-resistant Uropathogens Implicated in Asymptomatic Bacteriuria in Adults with Sickle Cell Disease in Ile-Ife, Southwest Nigeria

OBJECTIVES

We sought to determine the prevalence of asymptomatic bacteriuria (ASB) in patients with sickle cell disease (SCD), the susceptibility profile of its agents and their extended-spectrum β-lactamase (ESBL) production.

METHODS

Fifty-nine patients with SCD and 116 healthy controls were investigated. Urine samples were collected and cultured by standard techniques. We used the disc diffusion technique to determine antibiotic susceptibility. ESBL was detected by the combination disc method and detection of bla SHV, bla TEM, and bla CTX-M genes by multiplex-polymerase chain reaction.

RESULTS

The prevalence of ASB was higher among patients with SCD (8.6%) than controls (0.9%) (p = 0.016), predominantly among females. Coagulase-negative staphylococci (n = 2; 33.3%) predominated among the isolates. Other uropathogens included Stenotrophomonas maltophilia, Acinetobacter baumannii, and Enterobacter cloacae. All isolates were sensitive to meropenem but were resistant to ceftazidime, ampicillin, and tetracycline. bla SHV, bla TEM, and bla CTX-M-15 were detected in Enterobacter cloacae.

CONCLUSIONS

The prevalence of ASB is high in patients with SCD predominantly among females. Rare multidrug-resistant uropathogens were implicated. We posit a need for resistance surveillance programs and antibiotic stewardship to prevent treatment failure and reduce drug resistance.

Partial Red Blood Cell Exchange in Children and Young Patients with Sickle Cell Disease: Manual Versus Automated Procedure

INTRODUCTION

The benefits of manual versus automated red blood cell exchange have rarely been documented and studies in young sickle cell disease patients are scarce. We aim to describe and compare our experience in these two procedures.

MATERIAL AND METHODS

Young patients (≤ 21 years old) who underwent manual- or automated-red blood cell exchange for prevention or treatment of sickle cell disease complications were included. Clinical, technical and hematological data were prospectively recorded and analyzed.

RESULTS

Ninety-four red blood cell exchange sessions were performed over a period of 68 months, including 57 manual and 37 automated, 63 for chronic complications prevention, 30 for acute complications and one in the pre-operative setting. Mean decrease in sickle hemoglobin levels was higher in automated-red blood cell exchange (p < 0.001) and permitted a higher sickle hemoglobin level decrease per volume removed (p < 0.001), while hemoglobin and hematocrit remained stable. Ferritin levels on chronic patients decreased 54%. Most frequent concern was catheter outflow obstruction on manual-red blood cell exchange and access alarm on automated-red blood cell exchange. No major complication or alloimunization was recorded.

DISCUSSION

Automated-red blood cell exchange decreased sickle hemoglobin levels more efficiently than manual procedure in the setting of acute and chronic complications of sickle cell disease, with minor technical concerns mainly due to vascular access. The threshold of sickle hemoglobin should be individualized for clinical and hematological goals. In our cohort of young patients, the need for an acceptable venous access was a limiting factor, but iron-overload was avoided.

CONCLUSION

Automated red blood cell exchange is safe and well tolerated. It permits a higher sickle hemoglobin removal efficacy, better volume status control and iron-overload avoidance.

Hepatobiliary Ultrasonographic Abnormalities in Adult Patients with Sickle Cell Anaemia in Steady State in Ile-Ife, Nigeria

BACKGROUND

Sickle cell anaemia (SCA) is associated with structural manifestations in the hepatobiliary axis. This study aimed to investigate the hepatobiliary ultrasonographic abnormalities in adult patients with sickle cell anaemia in steady state attending the Haematology clinic of a federal tertiary health institution in Ile-Ife, Nigeria.

MATERIAL/METHODS

Basic demographic data as well as right upper abdominal quadrant ultrasonography of 50 consecutive sickle cell anaemia patients were compared with those of 50 age- and sex-matched subjects with HbAA as controls.

RESULTS

Each of the study groups (patients and controls) comprised of 21 (42%) males and 29 (58%) females. The age range of the patients was 18-45 years with a mean (±SD) of 27.6±7.607 years, while that of the controls was 21-43 years with a mean (±SD) of 28.0±5.079 years (p=0.746). Amongst the patients, 32 (64%) had hepatomegaly, 15 (30%) cholelithiasis and 3 (6%) biliary sludge. Fourteen (28%) of the patients had normal hepatobiliary ultrasound findings. In the control group, one (2%) person had cholelithiasis, one (2%) biliary sludge, one (2%) fatty liver and none hepatomegaly. Forty-seven (94%) of the controls had normal hepatobiliary ultrasound findings. There was a statistically significant difference in the prevalence of hepatomegaly and cholelithiasis between the patients and controls (p value <0.001 for both comparisons).

CONCLUSIONS

In this study, hepatomegaly, cholelithiasis and biliary sludge were the most common hepatobiliary ultrasound findings in patients with sickle cell anaemia. Ultrasonography is a useful tool for assessing hepatobiliary abnormalities in patients with sickle cell anaemia.

Bilateral mandibular osteomyelitis mimicking periapical cysts in a patient with sickle cell anemia

Sickle cell anemia (SCA) is a hemoglobin disorder that occurs more commonly among Afro-descendants. The authors report the case of a 28-year-old Afro-descendent male patient with the diagnosis of homozygotic sickle cell disease (SCD) referred for evaluation of mandibular lesions. The patient's main complaints included pain and bilateral teeth mobility. An intraoral examination revealed gingiva recession affecting the lower molars with extensive root exposure. A panoramic x-ray showed two radiolucent symmetrical periapical lesions evolving both the first and the second lower molars, bilaterally. The diagnostic hypotheses comprised odontogenic infection, among others. Besides antimicrobial therapy, the two molars of both sides were extracted and bone was collected for histopathological and microbiological analyses. Osteomyelitis was diagnosed, and Streptococcus viridans was recovered from the culture media. Mandibular osteomyelitis should be considered as a diagnosis in patients with SCD. The present case offers an alert to clinicians about the importance of knowing jaw lesions related to SCA.

Molecular analysis and association with clinical and laboratory manifestations in children with sickle cell anemia

OBJECTIVES

To analyze the frequency of β(S)-globin haplotypes and alpha-thalassemia, and their influence on clinical manifestations and the hematological profile of children with sickle cell anemia.

METHOD

The frequency of β(S)-globin haplotypes and alpha-thalassemia and any association with clinical and laboratorial manifestations were determined in 117 sickle cell anemia children aged 3-71 months. The confirmation of hemoglobin SS and determination of the haplotypes were achieved by polymerase chain reaction-restriction fragment length polymorphism, and alpha-thalassemia genotyping was by multiplex polymerase chain reaction (single-tube multiplex-polymerase chain reaction).

RESULTS

The genotype distribution of haplotypes was 43 (36.7%) Central African Republic/Benin, 41 (35.0%) Central African Republic/Central African Republic, 20 (17.0%) Rare/atypical, and 13 (11.1%) Benin/Benin. The frequency of the α3.7 deletion was 1.71% as homozygous (-α3.7/-α3.7) and 11.9% as heterozygous (-α3.7/αα). The only significant association in respect to haplotypes was related to the mean corpuscular volume. The presence of alpha-thalassemia was significantly associated to decreases in mean corpuscular volume, mean corpuscular hemoglobin and reticulocyte count and to an increase in the red blood cell count. There were no significant associations of β(S)-globin haplotypes and alpha-thalassemia with clinical manifestations.

CONCLUSIONS

In the study population, the frequency of alpha-thalassemia was similar to published data in Brazil with the Central African Republic haplotype being the most common, followed by the Benin haplotype. β(S)-globin haplotypes and interaction between alpha-thalassemia and sickle cell anemia did not influence fetal hemoglobin concentrations or the number of clinical manifestations.

Bone marrow necrosis and fat embolism: an autopsy report of a severe complication of hemoglobin SC disease

Sickle Cell Disease encompasses a group of disorders related with the hemoglobin S and other hemoglobin genotypes. The clinical manifestation and the severity of symptoms are dependent on the specific genotype. In this setting, homozygous genotype (HbSS) presents an early onset of symptoms and a low expectancy of lifetime. However, the SC genotype (HbSC), which apparently shows a less severe clinical course, may exhibit the same complications of HbSS. These complications are usually manifested late in the course of life, when compared with the HbSS patients. It is noteworthy that HbSC may present a normal hematocrit, and therefore stays unknown until the first complication, that may be disastrous. The authors report a case of an African-Descendant woman, aging 65 years, with no previous diagnosis of anemia who sought medical attention because of a thoracic back pain followed by fever and altered mental status. The clinical picture deteriorated very fast with multiple organ failure and death. The autopsy findings concluded by generalized vaso-occlusive crisis, bone marrow necrosis and bone marrow and fat embolism, mainly to the lungs and kidney. The authors call attention for the knowledge of this severe life threatening complication, mainly in a country with a high Afro-Descendant population.

Alpha chain hemoglobins with electrophoretic mobility similar to that of hemoglobin S in a newborn screening program

Objective

To characterize alpha-chain variant hemoglobins with electric mobility similar to that of hemoglobin S in a newborn screening program.

Methods

β^S allele and alpha-thalassemia deletions were investigated in 14 children who had undefined hemoglobin at birth and an electrophoretic profile similar to that of hemoglobin S when they were six months old. Gene sequencing and restriction enzymes (DdeI, BsaJI, NlaIV, Bsu36I and TaqI) were used to identify hemoglobins. Clinical and hematological data were obtained from children who attended scheduled medical visits.

Results

The following alpha chain variants were found: seven children with hemoglobin Hasharon [alpha2 47(CE5) Asp>His, HbA2:c.142G>C], all associated with alpha-thalassemia, five with hemoglobin Ottawa [alpha1 15(A13) Gly>Arg, HBA1:c.46G>C], one with hemoglobin St Luke's [alpha1 95(G2) Pro>Arg, HBA1:c.287C>G] and another one with hemoglobin Etobicoke [alpha212 84(F5) Ser>Arg, HBA212:c.255C>G]. Two associations with hemoglobin S were found: one with hemoglobin Ottawa and one with hemoglobin St Luke's. The mutation underlying hemoglobin Etobicoke was located in a hybrid α212 allele in one child. There was no evidence of clinically relevant hemoglobins detected in this study.

Conclusion

Apparently these are the first cases of hemoglobin Ottawa, St Luke's, Etobicoke and the α212 gene described in Brazil. The hemoglobins detected in this study may lead to false diagnosis of sickle cell trait or sickle cell disease when only isoelectric focusing is used in neonatal screening. Additional tests are necessary for the correct identification of hemoglobin variants.