Alpha-Thalassemia in North Morocco: Prevalence and Molecular Spectrum

Bridging the gaps in newborn screening programmes: Challenges and opportunities to detect haemoglobinopathies in Africa

Background

Haemoglobinopathies, including sickle cell disease and β-thalassaemia, are monogenic disorders with a relatively higher prevalence among malaria-endemic areas in Africa. Despite this prevalence, most African countries lack the necessary resources for diagnosing and managing these debilitating conditions.

Aim

This study provides a critical review of newborn screening for detecting haemoglobinopathies in Africa, highlighting challenges and proposing strategies for improved diagnosis and management.

Methods

A literature search on haemoglobinopathies in Africa was conducted in PubMed, Google Scholar and ScienceDirect, using specific keywords and Boolean operators, including articles published from January 1981 to December 2022.

Results

The data show that sickle cell disease is prevalent among populations in Central and West Africa; however, β-thalassaemia is prevalent among people in the northern parts of Africa. Newborn screening pilot initiatives for haemoglobinopathies were being implemented in Angola, Nigeria, Ghana, the Democratic Republic of Congo and the Republic of Benin. The cost of testing, lack of sufficient and accessible medical records, and inadequacy in healthcare infrastructure pose significant challenges in bridging the gaps in newborn screening. Furthermore, the stigmatisation and lack of awareness of haemoglobinopathies and access to newborn screening programmes pose additional challenges.

Conclusion

This review highlights the challenges associated with haemoglobinopathy testing, effective strategies for mitigating these challenges, and future perspectives for expanding efforts toward detecting and managing these disorders across Africa. Providing affordable diagnostic tools, mobile clinics, government subsidies, education campaigns, and the implementation of electronic medical records systems could help bridge the gaps in newborn screening in Africa.

What this study adds

The study presents a comprehensive view of newborn screening of haemoglobinopathies in Africa, provides a detailed outline of the challenges faced by newborn screening for haemoglobinopathies in Africa, and offers strategies for better diagnosis and care.

The Spectrum of α-Thalassemia Mutations in Syrian Patients

α-Thalassemia (α-thal) is a globally prevalent genetic disorder of hemoglobin (Hb) structure where the rate of α-globin chain synthesis is reduced or absent due to the presence of α-globin mutation(s). The aim of this study is to define the spectrum of α-globin gene mutations and evaluate their allele frequency in a group of α-thal carriers. A total of 55 individuals with possible α-thal patients were referred from the thalassemia centers in Syria. They have unexplained hypochromia and microcytosis. All patients were genetically tested for 21 common α-globin gene mutations using reverse hybridization kit. Seven different α-globin gene mutations and 13 different genotypes were detected in 55 patients. The two most frequently encountered mutations were -α3.7 deletion (47.1%) and --MED mutation (21.4%). The most commonly observed genotype was -α3.7/αα (40%), followed by --MED/αα genotype (21.8%). We determined the most common α thalassemia mutations in the Syrian patients. α-Thalassemia mutations with deletions were mostly observed in our study.

Genetic Analysis of Alpha-Thalassemia Mutations in Thi-Gar Province, Iraq

The prevalence of alpha-thalassemia as a major health problem in the south of Iraq has highlighted the necessity of investigations and screening of patients with thalassemia. The present study aimed to characterize the spectrum of alpha-globin gene mutations in patients who were followed up in a genetic diseases center in Thi-Qar province. A total of 30 subjects were collected from thalassemia patients and 15 cases as the control group. Polymerase chain reaction (PCR) and direct sequencing were performed for functionally regions of the gene (exon 1 and exon 2). The fragment size amplified was 442 bp in the Exon 1 region and 324 bp in the Exon 2 region of α-globin. The molecular analysis of the sequence of PCR products revealed that 13 point mutation within the α-thalassemia gene included deletion and substitution mutation, while the rest of the mutations were in the intron site of the gene. These results indicated that mutations may constitute a risk of developing hemophilia B disease. Molecular mechanisms in the expression of globin genes are used to help manage patients with thalassemia.

Alpha‐globin gene triplication and its effect in beta‐thalassemia carrier, sickle cell trait, and healthy individual

The genotype and phenotype correlation between coinheritance of heterozygous beta‐thalassemia with the alpha‐globin triplication is unclear. In this study we have investigated and reviewed alpha triplication frequency in beta‐thalassemia carriers, sickle cell trait, and healthy individuals and its effect on hematological and phenotypical changes. In this study, 4005 beta‐thalassemia carriers, 455 sickle cell trait, and 2000 healthy individuals were included. Molecular characterization of beta and alpha‐thalassemia was performed. The frequencies of alpha‐globin triplication in beta‐thalassemia carriers, sickle cell trait, and healthy individuals were 67 (1.67%), 4 (0.88%), and 18 (0.9%), respectively. In total, the frequency of alpha‐triplications is approximately 89 (1.39%) in Khuzestan province, South of Iran population. We have compared the average hematological parameters of beta‐thalassemia carriers, sickle cell trait, and healthy individuals with and without alpha gene triplication.

This mutation did not show any significant effect on the change of blood indices, neither in healthy individuals nor in sickle cell trait and beta‐thalassemia carriers. Therefore, there is no need to take more notice of anti 3.7 mutation in beta‐thalassemia carriers is opposed with some studies reported that the presence of excess alpha‐globin genes in beta‐thalassemia carriers can lead to the phenotype of beta‐thalassemia intermedia. Therefore, not every individual with triplicated alpha globin coinherited with beta‐thalassemia trait will have a significantly lower Hb than normal, and it is highly likely that none of them will need transfusion.

Epidemiology of thalassemia among the hill tribe population in Thailand

BACKGROUND

Thalassemia is a severe disease that occurs due to abnormalities in hemoglobin genes. Various genetic factors in different populations lead to different clinical manifestations of thalassemia disease, particularly among people who have a long history of migration and who have married among tribes, such as the hill tribe people in Thailand. This genetic epidemiological study aimed to estimate the prevalence of various forms of thalassemia among the six main hill tribe populations in Thailand.

METHODS

A cross-sectional study was conducted to obtain information and blood specimens from school children belonging to one of the six main hill tribes in Thailand: Akha, Lau, Hmong, Yao, Karen, and Lisu. Hill tribe children who were attending grades 4-6 in 13 selected schools in Chiang Rai Province, Thailand, were invited to participate in the study. A validated questionnaire and 3 mL blood specimens were collected after obtaining information consent forms from both the children and their parents on a voluntary basis. A complete blood count (CBC) was performed, followed by osmotic fragility (OF) and dichlorophenol indophenol precipitation (DCIP) tests to screen for thalassemia. High-performance liquid chromatography (HPLC) and real-time quantitative polymerase chain reaction (qPCR) were used to identify hemoglobin type and α-thalassemia, respectively. A t-test, chi-square and logistic regression were used to detect the associations between variables at the significance level of α = 0.05.

RESULTS

A total of 1,200 participants from 6 different tribes were recruited for the study; 50.0% were males, and 67.3% were aged 11-12 years. The overall prevalence of thalassemia carriers according to the screening tests was 9.8% (117 of 1,200). Among the cases, 83 were A2A (59 cases were α-thalassemia 1 carrier or α-thalassemia 2 carrier or homozygous α-thalassemia 2, and 24 cases were β-thalassemia trait with or without α-thalassemia); 1 case was EE (homozygous Hb E with or without α-thalassemia); 31 cases were EA (30 cases were the Hb E trait, and 1 case was Hb E trait with or without α-thalassemia); 1 case was A2A Bart's H (Hb H disease α-thalassemia 1/α-thalassemia 2); and 1 case was A2A with abnormal Hb. The prevalence of the α-thalassemia 1 trait among the hill tribe population was 2.5%. The greatest prevalence of the α-thalassemia 1 trait was found in the Karen (3.0%) and Hmong (3.0%) tribes.

CONCLUSIONS

The prevalence of some forms of thalassemia in the hill tribe population is higher than that in the Thai and other populations. Effective and available thalassemia screening tests, including essential information to protect the next generation through the specific counseling clinic, are crucial, particularly due to increasing marriages within these populations.

Empowering newborn screening programs in African countries through establishment of an international collaborative effort

In an effort to explore new knowledge and to develop meaningful collaborations for improving child health, the First Pan African Workshop on Newborn Screening was convened in June 2019 in Rabat, Morocco. Participants included an informal network of newborn screening stakeholders from across Africa and global experts in newborn screening and sickle cell disease. Over 150 attendees, representing 20 countries, were present including 11 African countries. The agenda focused on newborn screening rationale, techniques, system development, implementation barriers, ongoing research, and collaborations both globally and across Africa. We provide an overview of the workshop and a description of the newborn screening activities in the 11 African countries represented at the workshop, with a focus on sickle cell disease.

<p>Establishment and Evaluation of a Novel Method Based on Loop-Mediated Isothermal Amplification for the Rapid Diagnosis of Thalassemia Genes</p>

Purpose

Currently, thalassemia is commonly detected using gap-polymerase chain reaction (PCR) and deoxyribonucleic acid (DNA) reverse dot blot, which have high requirements of space, instruments, and personnel. Therefore, it is necessary to develop a new method for thalassemia detection with high sensitivity, low cost, and simple and fast operation. In this study, we aimed to design and evaluate a new method for detecting three α-thalassemia genes including –Southeast Asian (SEA), -α3.7, and -α4.2 and five β-thalassemia genes including 654M, 41/42M, −28M, 17M, and 27/28M based on loop-mediated isothermal amplification (LAMP).

Methods

Primer sequences were designed using Primer Explorer V4 software. Blood samples (5 mL) were collected from all participants in EDTA. DNA was extracted using Chelex 100 and was subjected to LAMP. LAMP products were detected by fluorescence development in ultraviolet light.

Results

We found that LAMP assays for positive samples of thalassemia reached a plateau before 60 minutes, whereas the negative control samples entered the plateau after 70 minutes or showed no amplification. The concentration range of positive reactions was between 20–60 pg/μL and 20–60 ng/μL. Additionally, there were no cross-reactivities among 8 thalassemia subtypes. For clinical samples, the positive sample tube showed strong green fluorescence, whereas the negative tube showed light green fluorescence. According to these results, the LAMP method has high sensitivity for detecting thalassemia (252/254). However, 43 false-positive results were obtained in the LAMP test. The LAMP assay was also of low cost and with simple and fast operation.

Conclusion

The novel LAMP assay can be completed within 60 min using a heating block or a water bath, and the result can be read visually based on color change to detect thalassemia. The LAMP assay fulfills the requirements of field application and resource-limited areas, especially those with primary hospitals and rural areas.

Hemoglobinopathies in the North of Morocco: Consanguinity Pilot Study

Consanguinity is a social behavior characterized by the arrangement of marriages between relatives. It coincides generally with the geographic distribution of recessive genetic diseases as it increases the likelihood of homozygosis and, consequently, the incidence of their pathologies in the population. In this pilot study, we assess the effect of inbreeding on the burden of hemoglobinopathies in Northern Morocco. From January 2016 to December 2018, 197 children born in the studied region to three ancestral generations and diagnosed with hemoglobinopathies were subject to investigation. The rate of consanguinity in the parents' generation of children with hemoglobinopathies was 50.25%, with first cousin marriages accounting for 68.69% of consanguineous unions (FI = 0.02). The corresponding rates in the general population, based on a sample of N = 900, were 29.67% and 82.02%, respectively. The marriages between first cousins are the most common among the other types of consanguineous unions. Our study propounds that consanguinity substantially contributes to the hemoglobinopathy burden in the studied region and has changed little over time. Refraining from consanguineous marriages and detecting couples at risk could contribute to the reduction of the incidence of genetic diseases in our country.