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

Kompetitive allele specific PCR (KASP) based genotyping of sickle gene in the selected sub-ethnic tribal population of Gujarat and Madhya Pradesh

BACKGROUND

Indian tribal population is more vulnerable to sickle cell disease (SCD), an autosomal recessive disease caused by a single A>T transversion mutation in the HBB gene. Current study aims to develop a novel Kompetitive allele specific PCR (KASP) assay for genotyping of sickle gene in selected tribal communities of India.

PATIENTS AND METHODS

The study was conducted from 2021 to 2023 involving 583 self-declared healthy individuals from four tribal communities, i.e. Korku, Kol, and Sahariya of Madhya Pradesh and Dongri bhil of Gujarat. The sickle cell genotyping was performed using KASP and PCR-RFLP methods and further validated by Sanger sequencing. Various hematological and biochemical parameters were also studied and compared for their association with identified genotypes.

RESULTS

Prevalence of sickle cell trait (SCT) was observed as 4.67%, 9.33%, and 16.41% in Kol, Korku, and Dongri bhil, respectively. The SCD prevalence of 0.7% was observed in Dongri bhil. The KASP assay reflects as a novel, high-throughput, and cost-effective method for effective screening. RBC, folic acid, fetal Hb (HBF), and bilirubin have shown significant association with sickle gene mutation.

CONCLUSIONS

KASP assay offers a rapid, precise, and cost-effective method for screening in tribal populations, which can help in early identification, management, and elimination of disease.

Dental tissues of sickle cell anemia and its impact on the quality of life related to oral health

OBJECTIVE

The aim of this study was to determine the association between dental tissues and sickle cell anemia (SCA) and how it impacts the quality of life related to oral health.

MATERIALS AND METHODS

It was a cohort study of 154 Congolese participants with and without SCA conducted in the dental service of SCA at the Yolo Center, Kinshasa, aged at least 6 years and without a history of clinically severe conditions (hospitalization and blood transfusion), who were regularly monitored. The inclusion criteria were the diagnosis confirmation of SCA at the health service in a period of at least 6 months before enrollment in this study. Dental tissues were assessed by a clinical examination using a dental mirror and probe. The index of Decayed-Missing-Filled Teeth (DMFT) was used to assess the dental state of the participants. For Oral Health-related Quality of Life (OHrQoL), the Congolese versions of the perception questionnaires, modified from the Oral Health Impacts Profile (OHIP-23), were used for participants. Each question had to be answered by yes or no, depending on whether the participant was satisfied (outcome = 1) or dissatisfied (outcome = 0) about an oral health-related quality of life.

RESULTS

Of the 154 participants, aged from 6 to 64 years, with a mean age of 19.5 ± 7 (SD) years, 96 presented with SCA and only 68 were correctly followed; 102 did not present SCA and only 86 were correctly followed. The DMFT and dmft indexes were higher in the SCA group, being 2.9 and 2.5, respectively. The difference between the SCA group and the control group was significant for decayed teeth, missing teeth, filled teeth and no caries. Of the different dimensions of quality of life that were compared between the SCA group and control group, 15 of 23 items were statistically significant.

CONCLUSION

The present study strongly confirmed an association between dental caries and missing teeth with sickle cell anemia. Secondly, the quality of life for SCA participants seems to be poor, compared to the control group.

Prevalence and genetic analysis of triplicated α-globin gene in Ganzhou region using high-throughput sequencing

α-globin gene triplication carriers were not anemic in general, while some studies found that α-globin gene triplication coinherited with heterozygous β-thalassemia may cause adverse clinical symptoms, which yet lacks sufficient evidence in large populations. In this study, we investigated the prevalence and distribution of α-globin gene triplication as well as the phenotypic characteristics of α-globin gene triplication coinherited with heterozygous β-thalassemia in Ganzhou city, southern China. During 2021-2022, a total of 73,967 random individuals who received routine health examinations before marriage were genotyped for globin gene mutations by high-throughput sequencing. Among them, 1,443 were α-globin gene triplication carriers, with a carrier rate of 1.95%. The most prevalent mutation was αααanti3.7/αα (43.10%), followed by αααanti4.2/αα (38.12%). 42 individuals had coinherited α-globin gene triplication and heterozygous β-thalassemia. However, they did not differ from the individuals with heterozygous β-thalassemia and normal α-globin (αα/αα) in terms of mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) levels. In addition, heterogenous clinical phenotypes were found in two individuals with the same genotype. Our study established a database of Ganzhou α-globin gene triplication and provided practical advice for the clinical diagnosis of α-globin gene triplication.

Effect of deletions in the α-globin gene on the phenotype severity of β-thalassemia

Thalassemia is the most common inherited hemoglobinopathy worldwide. Variation of clinical symptoms in this hemoglobinopathy entails differences in disease-onset and transfusion requirements. The aim of this study was to investigate the role of α-globin gene deletions in modulating the clinical heterogeneity of β-thalassemia (β-thal) syndromes. A total number 270 β-thal subjects were enrolled. Hematological parameters were recorded. β-Globin mutations were determined by amplified refractory mutation system-polymerase chain reaction (ARMS-PCR), gap-PCR and Sanger sequencing. α-Globin gene deletions were determined by multiplex PCR. Out of 270 β-thal subjects, 19 carried β⁺/β⁺, 74 had β⁰/β⁰ and 177 had the β⁰/β⁺ genotype. When we determined the severity of the different β-thal subjects in coinherited with the α gene deletion, it was revealed that, 84.2% β⁺/β⁺ subjects carried a non severe phenotype and did not have an α gene deletion. Of the β⁰/β⁰ individuals, 95.9% presented a severe phenotype, irrespective of α-globin gene deletions. In cases with the β⁰/β⁺ genotype, 19.2% subjects also carried a deletion on the α gene. Of these, 61.8% presented a non severe phenotype and 38.2% were severely affected. Only in the β⁰/β⁺ category did α gene deletions make a significant contribution (p < 0.001) toward alleviation of clinical severity. Therefore, it can be stated that α-globin gene deletions play a role in ameliorating the phenotype in patients with a β⁺/β⁰ genotype.

Global Globin Network Consensus Paper: Classification and Stratified Roadmaps for Improved Thalassaemia Care and Prevention in 32 Countries

The Global Globin Network (GGN) is a project-wide initiative of the Human Variome/Global Variome Project (HVP) focusing on haemoglobinopathies to build the capacity for genomic diagnosis, clinical services, and research in low- and middle-income countries. At present, there is no framework to evaluate the improvement of care, treatment, and prevention of thalassaemia and other haemoglobinopathies globally, despite thalassaemia being one of the most common monogenic diseases worldwide. Here, we propose a universally applicable system for evaluating and grouping countries based on qualitative indicators according to the quality of care, treatment, and prevention of haemoglobinopathies. We also apply this system to GGN countries as proof of principle. To this end, qualitative indicators were extracted from the IthaMaps database of the ITHANET portal, which allowed four groups of countries (A, B, C, and D) to be defined based on major qualitative indicators, supported by minor qualitative indicators for countries with limited resource settings and by the overall haemoglobinopathy carrier frequency for the target countries of immigration. The proposed rubrics and accumulative scores will help analyse the performance and improvement of care, treatment, and prevention of haemoglobinopathies in the GGN and beyond. Our proposed criteria complement future data collection from GGN countries to help monitor the quality of services for haemoglobinopathies, provide ongoing estimates for services and epidemiology in GGN countries, and note the contribution of the GGN to a local and global reduction of disease burden.

Co-Inheritance of α-thalassemia gene mutation in patients with sickle cell Disease: Impact on clinical and hematological variables

Background

Sickle cell disease (SCD) is a monogenic, phenotypically highly variable disease with multisystem pathology. The phenotypic heterogeneity of SCD is attributed to environmental and genetic factors such as fetal hemoglobin and co-inheritance of α-thalassemia.

Objectives

To look for different types of α-thalassemia gene mutations among SCD patients and evaluate the influence of the co-inheritance of α-thalassemia on clinical and hematological variables.

Methods

This cross-sectional analytical study included 765 SCD patients, and 150 patients (with low mean corpuscular volume (MCV), low mean corpuscular hemoglobin (MCH) and normal serum ferritin levels) were tested for α-thalassemia gene mutations. Multiplex PCR and reverse hybridization and sequencing for both α genes using the Vienna Lab Strip Assay PCR study were performed using conventional PCR technology.

Results

Out of 150 patients tested for α-thalassemia gene mutations, 141 patients were found to have one or more of the mutational types, representing 18.4% of all studied SCD patients. The most common mutations found were the -^3.7 deletion (76.6%), followed by the -^4.2 deletion (12.1%), mutant α2^polyA-1 (Saudi type) (9.2%), and --^MED double gene deletion (7.8%). Acute painful episodes did not differ significantly in sickle cell anemia (SCA) patients with or without α-thalassemia, although the co-inheritance of α-thalassemia has a protective role against many disease-related complications. However, this role was not observed with other types of SCD. The means of red blood cell count, hemoglobin, and hematocrit were significantly higher, while the MCV, MCH, reticulocyte count, and hemoglobin A2 percentage were significantly lower in patients with α-thalassemia gene mutations than in those without α-thalassemia gene mutations (P < 0.05).

Conclusions

The co-inheritance of α-thalassemia and SCA confers protection against many disease-related complications and is associated with improved hematological indices. However, this protection was not noticed in patients with other types of SCD.

Association of alpha-thalassemia and Glucose-6-Phosphate Dehydrogenase deficiency with transcranial Doppler ultrasonography in Nigerian children with sickle cell anemia

Background

Stroke is a devastating complication of sickle cell anemia (SCA) and can be predicted through abnormally high cerebral blood flow velocity using transcranial Doppler Ultrasonography (TCD). The evidence on the role of alpha‐thalassemia and glucose‐6‐phosphate dehydrogenase (G6PD) deficiency in the development of stroke in children with SCA is conflicting. Thus, this study investigated the association of alpha‐thalassemia and G6PD(A⁻) variant with abnormal TCD velocities among Nigerian children with SCA.

Methods

One hundred and forty‐one children with SCA were recruited: 72 children presented with normal TCD (defined as the time‐averaged mean of the maximum velocity: < 170 cm/s) and 69 children with abnormal TCD (TAMMV ≥ 200 cm/s). Alpha‐thalassemia (the α‐3.7 globin gene deletion) was determined by multiplex gap‐PCR, while G6PD polymorphisms (202G > A and 376A > G) were genotyped using restriction fragment length polymorphism—polymerase chain reaction.

Results

The frequency of α‐thalassemia trait in the children with normal TCD was higher than those with abnormal TCD: 38/72 (52.8%) [α‐/ α α: 41.7%, α ‐/ α ‐: 11.1%] versus 21/69 (30.4%) [α‐/ α α: 27.5%, α ‐/ α ‐: 2.9%], and the odds of abnormal TCD were reduced in the presence of the α‐thalassemia trait [Odds Ratio: 0.39, 95% confidence interval: 0.20–0.78, p = 0.007]. However, the frequencies of G6PDA⁻ variant in children with abnormal and normal TCD were similar (11.6% vs. 15.3%, p = 0.522).

Conclusion

Our study reveals the protective role of α‐thalassemia against the risk of abnormal TCD in Nigerian children with SCA.

Co-Inheritance of alpha-thalassemia and sickle cell disease in a cohort of Angolan pediatric patients

The aim of this study was to explore the association between alpha-thalassemia, fetal hemoglobin, hematological indices, and clinical adverse events in Angolan sickle cell disease pediatric patients. A total of 200 sickle cell disease (SCD) children were sampled in Luanda and Caxito. A venous blood sample was collected and used for hematological analyses, fetal hemoglobin quantification, and genotyping of 3.7 kb alpha-thalassemia deletion by GAP-PCR. The frequency of the 3.7 kb alpha-thalassemia deletion in homozygosity was 12.5% and in heterozygosity was 55.0%. An increase in alpha-thalassemia frequency was observed in children older than 5 years old (11.7% vs. 13.00%). Furthermore, 3.7 kb alpha-thalassemia deletion homozygotes had a significantly higher age of the first manifestation, lower number of blood transfusions by year, higher hemoglobin, lower mean corpuscular volume, mean corpuscular hemoglobin, and lower hemolytic rate observed by a lower number of reticulocytes count. There were no differences in fetal hemoglobin between the three genotypes. Moreover, the number of stroke events, osteomyelitis, splenomegaly, splenectomy, and hepatomegaly were lower when alpha-thalassemia was co-inherited. For the first time in Angolan population, the effect of alpha-thalassemia deletion in sickle cell disease was analyzed and results reinforce that this trait influences the hematological and clinical aspects and produces a milder phenotype.

Homozygous Deletion Alpha-Thalassemia and Hereditary Persistence of Fetal Hemoglobin, Two Genetic Factors Predictive the Reduction of Morbidity and Mortality During Pregnancy in Sickle Cell Patients. A Report from the Democratic Republic of Congo

OBJECTIVE

to determine the beneficial role of Fetal Hemoglobin (FHb) and alpha-thal on fetal and maternal morbidity during pregnancy in sickle cell patients.

STUDY SITE

the study was conducted at the sickle cell center of Kinshasa between 2008 and 2018.

SETTING AND STUDY POPULATION

this is a documentary and analytical study that included 980 deliveries of homozygous sickle cell patients.

METHODS

the diagnosis of SCD and the quantification of FHb were performed with the capillary electrophoresis technique. The molecular test confirmed the diagnosis of SCD. The diagnosis of alpha-thal was made with the multiplex ligation-dependent probe amplification (MLPA) technique. Sickle cell pregnancies were followed according to the protocol of care in force in the University of Kinshasa Hospital service. The variables of interest were: hematological variables, sickle cell crises during pregnancy, maternal and fetal complications.

STATISTICS

statistical analyses were performed with SPSS 20.0 software. Means and standard deviations were compared with the Student's t and ANOVA tests. The value of p <0.05 was considered the significance level.

RESULTS

the Hb-SS / alpha-thal and HbSS / HPFH genotypes were observed in 101 and 121 women, respectively. Otherwise, 758 women had HbSS genotype. The morbidity related to sickle cell complications in the mother and fetus were less frequent in the Hb-SS / alpha-thal and HbSS / HPFH groups than in HB-SS group. The differences were statistically significant.

CONCLUSION

this study showed a significant protective effect of alpha-thal and HPFH during pregnancy in sickle-cell pregnant women.

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.