Alpha thalassemia among sickle cell anaemia patients in Kampala, Uganda

Pseudoxanthoma elasticum - Genetics, pathophysiology, and clinical presentation

Pseudoxanthoma elasticum (PXE) is an autosomal-recessively inherited multisystem disease. Mutations in the ABCC6-gene are causative, coding for a transmembrane transporter mainly expressed in hepatocytes, which promotes the efflux of adenosine triphosphate (ATP). This results in low levels of plasma inorganic pyrophosphate (PPi), a critical anti-mineralization factor. The clinical phenotype of PXE is characterized by the effects of elastic fiber calcification in the skin, the cardiovascular system, and the eyes. In the eyes, calcification of Bruch's membrane results in clinically visible lesions, including peau d'orange, angioid streaks, and comet tail lesions. Frequently, patients must be treated for secondary macular neovascularization. No effective therapy is available for treating the cause of PXE, but several promising approaches are emerging. Finding appropriate outcome measures remains a significant challenge for clinical trials in this slowly progressive disease. This review article provides an in-depth summary of the current understanding of PXE and its multi-systemic manifestations. The article offers a detailed overview of the ocular manifestations, including their morphological and functional consequences, as well as potential complications. Lastly, previous and future clinical trials of causative treatments for PXE are discussed.

Genetic Variation and Sickle Cell Disease Severity: A Systematic Review and Meta-Analysis

Importance

Sickle cell disease (SCD) is a monogenic disorder, yet clinical outcomes are influenced by additional genetic factors. Despite decades of research, the genetics of SCD remain poorly understood.

Objective

To assess all reported genetic modifiers of SCD, evaluate the design of associated studies, and provide guidelines for future analyses according to modern genetic study recommendations.

Data Sources

PubMed, Web of Science, and Scopus were searched through May 16, 2023, identifying 5290 publications.

Study Selection

At least 2 reviewers identified 571 original, peer-reviewed English-language publications reporting genetic modifiers of human SCD phenotypes, wherein the outcome was not treatment response, and the comparison was not between SCD subtypes or including healthy controls.

Data Extraction and Synthesis

Data relevant to all genetic modifiers of SCD were extracted, evaluated, and presented following STREGA and PRISMA guidelines. Weighted z score meta-analyses and pathway analyses were conducted.

Main Outcomes and Measures

Outcomes were aggregated into 25 categories, grouped as acute complications, chronic conditions, hematologic parameters or biomarkers, and general or mixed measures of SCD severity.

Results

The 571 included studies reported on 29 670 unique individuals (50% ≤ 18 years of age) from 43 countries. Of the 17 757 extracted results (4890 significant) in 1552 genes, 3675 results met the study criteria for meta-analysis: reported phenotype and genotype, association size and direction, variability measure, sample size, and statistical test. Only 173 results for 62 associations could be cross-study combined. The remaining associations could not be aggregated because they were only reported once or methods (eg, study design, reporting practice) and genotype or phenotype definitions were insufficiently harmonized. Gene variants regulating fetal hemoglobin and α-thalassemia (important markers for SCD severity) were frequently identified: 19 single-nucleotide variants in BCL11A, HBS1L-MYB, and HBG2 were significantly associated with fetal hemoglobin (absolute value of Z = 4.00 to 20.66; P = 8.63 × 10-95 to 6.19 × 10-5), and α-thalassemia deletions were significantly associated with increased hemoglobin level and reduced risk of albuminuria, abnormal transcranial Doppler velocity, and stroke (absolute value of Z = 3.43 to 5.16; P = 2.42 × 10-7 to 6.00 × 10-4). However, other associations remain unconfirmed. Pathway analyses of significant genes highlighted the importance of cellular adhesion, inflammation, oxidative and toxic stress, and blood vessel regulation in SCD (23 of the top 25 Gene Ontology pathways involve these processes) and suggested future research areas.

Conclusions and Relevance

The findings of this comprehensive systematic review and meta-analysis of all published genetic modifiers of SCD indicated that implementation of standardized phenotypes, statistical methods, and reporting practices should accelerate discovery and validation of genetic modifiers and development of clinically actionable genetic profiles.

The clinical characteristics of Congolese children and adolescents suffering from sickle-cell anemia are marked by the high frequencies of epistaxis compared to Western series

Background: Sickle cell anaemia (SCA) is the most common genetic diseases in the Democratic Republic of Congo (DRC). It is estimated 30,000 to 40,000 neonates with SCA are born annually. Despite this high incidence rate, and the severity of the Bantu haplotype found in Congolese patients, major clinical characteristics remain poorly defined. The objective of this study was to assess the clinical and haematological profile of the SCA in patients less than 24 years of age. Methods: A cross-sectional study was conducted in Kinshasa, the large city of the DRC. Patients were consecutively selected in three health institutions. Results: The study includes 256 sickle cell patients. The mean age of 8.4 (SD = 4.9) years. The Hand-foot syndrome was most common (52.7%) first presentation revealing the disease in our series. The most prevalent crises found in our series were vaso-occlusive crises (VOC) in 170 cases (66.4%) and severe hemolysis in 136 cases (53.1%). Splenic sequestration was noted in 19 cases (7.4%). The age at the first pain crisis was 18.2±15.2 months-of-age and the age at the first transfusions was 29.2±27.6 months-of -age. The most common signs associated with sickle cell disease in our series were hepatomegaly (53.9%), splenomegaly (41.7%), and adenotonsillar hypertrophy (34.8%). Epistaxis was reported in 9.4%. Conclusion: The clinical course of patients in DRC was comparable to reports from Western countries, with the notable exception of epistaxis which was significantly higher in patients in the DRC.

Beta Thalassemia Major with Gaucher's Disease: A Rare Entity

Thalassemia is a genetic disorder due to deletion or mutation in the gene for alpha or beta chain of hemoglobin. Gaucher's disease (GD) is characterized by a deficiency of a lysosomal enzyme, glucocerebrosidase which occurs due to mutations in the GBA1 gene on chromosome 1. Thalassemia and GD have overlapping clinical manifestations and present with features such as anemia, hepatosplenomegaly, and skeletal involvement. This creates a diagnostic conundrum for physicians. We present a case of an 11-month-old female who presented with fever, increasing paleness, and labored breathing. She had a recent history of uncross-matched transfusion. The child showed signs of anemic failure. Physical exam findings strongly pointed towards hemolytic anemia due to thalassemia major. Genetic analysis confirmed homozygosity in Fr 8-9 mutation confirming beta thalassemia major. Bicytopenia along with visceromegaly indicated malaria or storage diseases. Enzyme analysis revealed low levels of beta-glucocerebrosidase with normal acid sphingomyelinase levels confirming GD. In our case, we report the association of beta thalassemia major with GD which is a rare entity. The report highlights the need for an independent assessment of disorders that have similar presentations to avoid missing an associated disorder.

Influence of alpha thalassemia on clinical and laboratory parameters among nigerian children with sickle cell anemia

BACKGROUND

There is paucity of data on the influence of alpha thalassemia on the clinical and laboratory parameters among Nigerian sickle cell anemia (SCA) patients. This study aimed to determine the prevalence of alpha thalassemia and the influence of alpha thalassemia on laboratory parameters and clinical manifestations in a group of young Nigerian SCA patients.

METHODS

This was a cross-sectional retrospective study conducted on 100 patients with SCA and 63 controls. The diagnosis of SCA was confirmed by DNA studies. Alpha thalassemia genotyping was performed by multiplex gap-PCR method. Laboratory parameters including complete blood count, hemoglobin quantitation, serum lactate dehydrogenase (LDH), and bilirubin were determined with standard techniques.

RESULTS

Alpha thalassemia was found in 41 (41.0%) patients compared to 24 (38.1%) controls (P = 0.744), and all were due to the 3.7 κb α-globin gene deletions. Alpha thalassemia was associated with more frequent bone pain crisis, higher hemoglobin concentration, red blood cell count, and HbA₂ level among the patients. On the contrary, patients with alpha thalassemia had lower mean corpuscular volume, mean corpuscular hemoglobin, and white blood cell count (WBC) (P ˂ 0.05). There were 6 (6.0%) patients with leg ulcers, and none of them had alpha thalassemia, P = 0.04.

CONCLUSION

This study confirms that coexistence of alpha thalassemia with SCA significantly influences both the clinical and laboratory manifestations of young Nigerian SCA patients. The coexistence of this genetic modifier is associated with increased bone pain crisis and protects against sickle leg ulcers among the patients.

Association between sickle cell anemia and alpha thalassemia reveals a high prevalence of the α3.7 triplication in congolese patients than in worldwide series

BACKGROUND

Information about the association with alpha thalassemia in sickle cell patients is unknown in the Democratic Republic of Congo. There is very little data on the alpha thalassemia in patients suffering from sickle cell anemia in Central Africa, and their consequences on the clinical expression of the disease.

METHODS

A cross-sectional study was conducted in 106 sickle cell patients living in the country's capital Kinshasa. The diagnosis of sickle cell anemia was confirmed with a molecular test using PCR-RFLP (restriction fragment length polymorphism) technique. The diagnosis of thalassemia was performed by the technique of multiplex ligation dependent probe amplification.

RESULTS

The mean age of our patients was 22.4±13.6 years. The α3.7 heterozygous deletion, the α3.7 homozygous deletion and the α3.7 triplication were respectively encountered in 23.6%, 25.5% , and 11.3% of patients. Patients with normal αα/αα genotype represented 39.6% of the study population. The average of severe vaso-occlusive crises, the rates of blood transfusions per year, the rate of osteonecrosis, cholelithiasis and leg ulcers were significantly lower in the group of patients with α3.7 homozygous deletion and α3.7 triplication.

CONCLUSION

The prevalence of α3.7 triplication was higher in sickle cell patients in the Democratic Republic of Congo than in worldwide series. The α3.7 triplication and α3.7 homozygous deletion were associated with less severe forms of the Sickle cell anemia in Congolese patients. These results showed the need to investigate systematically the alpha-globin gene mutations in sickle cell population in Central Africa.

Sickle-cell and alpha-thalassemia traits resulting in non-atherosclerotic myocardial infarction: Beyond coincidence?

Alpha-thalassemia trait and sickle trait are not commonly considered risk factors of ischemic heart disease. We report the case of a non-atherosclerotic silent myocardial infarction in a 46-year-old woman, carrier of the alpha-thalassemia trait (homozygous deletion of locus -3.7) combined with sickle cell trait. While the patient was included as healthy volunteer for a metabolic study, we performed cardiac magnetic resonance imagery showing a left ventricle apicolateral myocardial infarction. Coronary computed tomography angiography showed normal coronary arteries with a coronary calcium score of 0. The patient was treated with low-dose aspirin in secondary prevention afterwards. This case allows us to discuss cardiovascular risk among patients presenting with both alpha-thalassemia trait and sickle cell trait and the indication of cardiac imagery in such patients even when considered as low-cardiovascular risk.

Variability of homozygous sickle cell disease: The role of alpha and beta globin chain variation and other factors

The single base molecular substitution characterizing sickle cell haemoglobin, β⁶glu→val, might be expected to result in predictable haematological and clinical features. However, the disease manifests remarkable diversity believed to reflect the interaction with other genetic and environmental factors. Some of the genetic modifiers include the beta globin haplotypes, alpha thalassaemia, factors influencing the persistence of fetal haemoglobin and the effects of the environment are addressed in this review. It is concluded that much of the genetic data present conflicting results. Environmental factors such as climate and infections, and psychological, educational and social support mechanisms also influence expression of the disease. These interactions illustrate how the expression of a 'single gene' disorder may be influenced by a variety of other genetic and environmental factors.

Factors Associated with Growth Retardation in Children Suffering from Sickle Cell Anemia: First Report from Central Africa

Background. The aim of this study was to investigate and determine the risk factors associated with poor growth among SCA children. Methods. A cross-sectional study was conducted in Kinshasa, the capital's country. The nutritional status was assessed using the Z scores of the anthropometric indices. Results. We gathered data on the 256 patients, 138 females (53.9%), who entered the study. The mean age at presentation was 8.4 ± 4.9 years of age. Underweight, stunting, and wasting were found, respectively, in 47.7%, 10.5%, and 50.3% of SCA children. A history of hand-foot syndrome, more than 3 blood transfusions, being less than 12 months of age when receiving the first transfusion, more than two severe sickle crises per year, a medical history of severe infections, and the presence of hepatomegaly were associated with poor growth. When comparing sickle cell patients under 12 years of age (n = 159) to a group of 296 age-matched children with normal Hb-AA, a significantly higher proportion of subjects with stunting and underweight were found among SCA. Conclusion. Nutritional status encountered in Congolese sickle cell children has been described for the first time in this study. A high prevalence of poor growth in SCA children was found in our study.

A retinopathy in young patient with co-inheritance of heterozygous alpha + -thalassemia and sickle trait: a case report

Background

The retinopathy is an uncommon complication in individuals with sickle cell trait except for the cases of sickle cell trait associated with systemic arterial hypertension, diabetes mellitus, syphilis, tuberculosis and sarcoidosis.

Case Presentation

A retinopathy in a 16 year-old child with no history of consanguinity in the parents revealed a sickle S trait associated to heterozygous alpha thalassemia. His mother has Sickle cell anaemia (Hb SS) and his father is a carrier of heterozygous alpha-thalassemia status that it was unknown before.

Conclusion

This case report describes a proliferative retinopathy in a 16 year-old patient with co-inheritance of heterozygous alpha + −thalassemia and sickle trait.