Molecular Heterogeneity of Beta-Thalassemia in the United Arab Emirates

Going Back to Fundamentals: Three Marriageable Actions for Thalassemia and Carrier Population Management

We investigated the impact of three marriageable actions: normal-to-carrier, carrier-to-normal, and carrier-to-carrier marriages on thalassemia and carrier populations. The well-known strategy is limiting the carrier-to-carrier marriage to reduce the thalassemia population. Thus, the other two marriageable actions were often ignored. Other than a simple explanation of their genetic consequences, their important aspect in the thalassemia inheritance mechanism has never been studied at the population level. Moreover, there is no mathematical model investigating problem of interest for blood disorders at the population level. Hence, we developed a mathematical model to examine the possibility of eradication/reduction of thalassemia and carrier populations through each of the three marriageable actions in the long-term. We conducted computer simulations with the demographic data of the United Arab Emirates in which high thalassemia carrier prevalence is identified. We found that promoting more carrier-to-normal marriage will eventually have the same effects on marriage reconsideration for carrier-carrier couples, contributing to the reduction of the carrier population in the long-term. Interestingly, the normal-to-carrier marriage does not necessarily have a similar effect on thalassemia and carrier populations as that of the carrier-to-normal marriage. Thus, the two marriageable actions should be distinguished and also seriously considered in education and public awareness campaigns for thalassemia.

Molecular heterogeneity of β-thalassemia variants in the Eastern region of Morocco

Background

β‐thalassemia syndromes are the most common hereditary blood disorders in the world and are recognized as a major health problem in Morocco. They are characterized by the reduction or the absence of β‐globin chain synthesis. The severity of the disease depends on the nature of the variants affecting the β‐globin gene (HBB), and each ethnic group has its own mutation spectrum. Hereby, we present, for the first time, the molecular profile of β‐thalassemia in the Eastern region of Morocco.

Methods

This study concerns 39 cases from 33 families who were enrolled in the BRO Biobank. Nineteen were diagnosed with β‐thalassemia major and 20 with β‐thalassemia minor. To detect mutations of the β‐globin gene, we have used RFLP‐PCR and Sanger sequencing.

Results

Nine known β‐thalassemia variants have been identified. Among these, we reported, for the first time in the Moroccan population, the Czechoslovakian variant C38/39(‐C) at homozygous state. The C39(C > T) was the most frequent variant (72.54%), followed by FSC5(‐CT) (5.88%), FSC6(−A), IVS‐1‐110(G > A), −29(A > G), C38/39(‐C) (3.92% each), and finally by IVS‐I‐1(G > A), IVS‐II‐1(G > A), and −56(G > C) (1.96%). Of particular interest this mutational spectrum of β‐thalassemia is very different from that found in previous studies in Morocco or in other North African countries.

Conclusion

This study is the first contribution to the description of the molecular profile of β‐thalassemia in the Eastern region of Morocco. It shows the high molecular heterogeneity of β‐thalassemia in our country. Therefore, these results can be valuable for the implementation of carrier screening, genetic counseling, and prenatal diagnosis programs.

The spectrum of beta-thalassemia mutations in the 22 Arab countries: a systematic review

OBJECTIVES

To investigate the mutational spectrum in the HBB gene in Arab patients with β-thal.

METHODS

Authors searched five databases (PubMed, Science Direct, Scopus, Web of Science, and Google Scholar) from the time of inception until March 2020.

RESULTS

The authors search strategy yielded 3,229 citations, of which 48 eligible studies captured. 105 mutations were captured, of these, 99 were shared between Arabs and other ethnic groups, six mutations were unique to Arabs (c.92 + 2 T > G, c.-240 G > A, c.150delC, c.420dupT, deletion of 192 bp spanning exon 1, intron 1, and the first two bases of exon 2 of HBB gene, and deletion of 9.6 kb, including exon 1 and intron 2 of HBB gene). The most common HBB gene mutations among Arabs were c.93-21 G > A, c.118 C > T, c.92 + 1 G > A, c.92 + 6 T > C, c.92 + 5 G > C, c.315 + 1 G > A, and c.27dupG. Consanguinity is high among Arab patients with β-thal. Migration into Arab countries led to allelic heterogeneity among Arab patients with β-thal.

CONCLUSION

Our findings present a platform for further genetic epidemiological studies for Arab patients with β-thal.

Epidemiology of Thalassemia in Gulf Cooperation Council Countries: A Systematic Review

Background

Thalassemia has a burden on the healthcare systems of many countries. About 56000 conceptions result in thalassemia, globally.

Objective

To assess the epidemiological profile of thalassemia in the Gulf Cooperation Council (GCC) countries.

Methods

A systematic search was conducted in MEDLINE/PubMed (National Library of Medicine), CINAHL, and Embase. Relevant observational studies reporting the epidemiology of thalassemia among the GCC population were selected. Data on the prevalence, frequency, and complications of thalassemia were extracted. The quality of the retrieved studies was assessed according to the Newcastle-Ottawa Quality Assessment Scale.

Results

Eighteen studies (14 cross-sectional studies, two retrospective observational studies, and two retrospective analysis) with a total of 3343042 participants were included in this systematic review. Of the 18 studies, 11 studies were conducted in Saudi Arabia, two in the Kingdom of Bahrain, one in Kuwait, three in the United Arab Emirates (UAE), and one in Qatar. The prevalence of thalassemia among children below five years of age ranged from 0.25% to 33%, while it was 0.9% in children above five years and from 0.035% to 43.3% among adult thalassemia patients. The most-reported risk factors were consanguineous marriage and high-risk marriage. There was a lack of data regarding mortality rates in thalassemia.

Conclusions

Despite the premarital screening and genetic counseling (PMSGC) program for thalassemia, the incidence of high-risk couple marriages in GCC countries cannot be effectively diminished. This study suggested that the PMSGC program should adopt more attention for the high-risk areas, to enhance the level of consciousness about the hemoglobinopathy diseases and the consequences of consanguinity among the at-risk couple.

Improved efficiency and patient safety through bespoke electronic thalassaemia care module

Objectives

To investigate the impact of electronic medical record (EMR) on improvement of healthcare parameters in a thalassaemia centre located at the Fujairah Hospital, Fujairah, UAE.

Materials and methods

A hospital-wide EMR system (Wareed) was implemented across the hospitals in the Ministry of Health and Prevention, UAE, including two major thalassaemia centres. We aim to investigate the impact of this intervention across a number of healthcare parameters over two quarters (before and after implementation of the system).

Results

Since preimplementation data were not available for one facility, comparisons were made between parameters in two quarters in Fujairah hospital only. After introduction of Wareed, we found an increase in number of appointments (12%) (p=0.00), decrease in the number of appointment cancellations due to non-availability of blood products (p=0.02), reduction in the time to cannulation (p=0.00), decrease in number of physician days (p=0.295) among other parameters observed.

Discussion

Research shows that EMR systems have a positive impact on reduction in medical expenditure, improvement of healthcare quality and overall health outcomes. thalassaemia is highly prevalent in the Middle Eastern countries and drains the medical, social and financial resources of these nations. Our study is an attempt to create an insight into the difference in healthcare parameters before and after introduction of the system.

Conclusion

Being the first of a kind in this region, our study created favourable evidence that introduction of an EMR has an overall positive impact on the healthcare delivery system for thalassaemia care.

Thalassemia in the United Arab Emirates: Why it can be prevented but not eradicated

Thalassemia is a genetic blood disorder that causes abnormal hemoglobin. Hemoglobin is a protein in red blood cells that carries oxygen and is made of two proteins from four α-globin genes and two β-globin genes. A defect in one or more of these genes causes thalassemia. The treatment of thalassemia mostly depends on life-long blood transfusions and removal of excessive iron from the blood stream. Such tremendous blood consumption puts pressure on the national blood stock in many countries. In particular, in the United Arab Emirates (UAE), various forms of thalassemia prevention have been used and hence, the substantial reduction of the thalassemia major population has been achieved. However, the thalassemia carrier population still remains high, which leads to the potential increase in the thalassemia major population through carrier-carrier marriages. In this work, we investigate the long-term impact and efficacy of thalassemia prevention measures via mathematical modeling at a population level. To our best knowledge, this type of assessment has not been done before and there is no mathematical model that has investigated such a problem for thalassemia or any blood disorders at a population level. By using UAE data, we perform numerical simulations of our model and conduct sensitivity analysis of parameter values to see which parameter values affect most the dynamics of our model. We discover that the prevention measures can contribute to reduce the prevalence of the disease only in the short term but not eradicate the disease in the long term.

Regional consensus opinion for the management of Beta thalassemia major in the Arabian Gulf area

Thalassemia syndrome has diverse clinical presentations and a global spread that has far exceeded the classical Mediterranean basin where the mutations arose. The mutations that give rise to either alpha or beta thalassemia are numerous, resulting in a wide spectrum of clinical severity ranging from carrier state to life-threatening, inherited hemolytic anemia that requires regular blood transfusion. Beta thalassemia major constitutes a remarkable challenge to health care providers. The complications arising due to the anemia, transfusional iron overload, as well as other therapy-related complications add to the complexity of this condition. To produce this consensus opinion manuscript, a PubMed search was performed to gather evidence-based original articles, review articles, as well as published work reflecting the experience of physicians and scientists in the Arabian Gulf region in an effort to standardize the management protocol.

β-Thalassemia in Abu Dhabi: consanguinity and tribal stratification are major factors explaining the high prevalence of the disease

Tribalism and consanguineous marriages are common in parts of the world with a high prevalence of the β-thalassemia (β-thal) mutations, and increase the risks of homozygosity for this and other recessive disorders. We explored the frequency of β-thal genes and β-thal carriers in 5672 subjects screened before marriage, of whom 2262 were couples. The mean coefficient of inbreeding (F) in the population was estimated from self-reported relationships to prospective spouses in 383 subjects. Overall frequency of β-thal mutations and β-thal carriers in the population were 1.16 and 2.3%, respectively. Among the 14 largest tribes, β-thal carrier frequencies varied from 0 to 13.6%. The estimated F in the population was 0.022. The expected number of couples needed to be screened to detect one couple who were both β-thal carriers in the non inbreeding (F = 0) and inbreeding (F = 0.022) population was 1858 and 646, respectively. However, among 2262 couples, 10 were both β-thal carriers, i.e., 1 in 226 couples, significantly (p = 0.02) more than expected by taking only inbreeding into account. Although β-thal mutations are relatively rare, the burden of β-thal disease is increased eight-fold by tribalism and consanguinity.

Hemoglobin A2 Lowered by Iron Deficiency and α -Thalassemia: Should Screening Recommendation for β -Thalassemia Change?

Screening for β-thalassemia trait (BTT) relies on measuring hemoglobin (Hb) A₂. Since multiple factors can affect HbA₂ levels, the screening can become unreliable. In 1356 healthy Arabs enrolled into a federally funded premarital BTT screening program, the effects of iron deficiency (ID), α⁺-thalassemia trait, gender, smoking, and tribalism on HbA₂ were studied. The complete blood count and hemoglobin fractions were determined on the entire cohort; serum ferritin (<15 μg/L) in 391 subjects was used to determine ID. BTT was present in 29 (2.1%) subjects (HbA₂ > 3.5%). Among 77(20.3%) subjects with ID, the mean HbA₂ (2.30 ± 0.23%) was 0.2% lower than in subjects without iron deficiency (2.50 ± 0.24%, P < 0.0001). In 65 (38%)/172 subjects with phenotypic α⁺-thalassemia trait, the mean HbA₂ (2.43 ± 0.24%) was 0.13% lower than in subjects without α⁺-thalassemia trait, P < 0.0001. The mean HbA₂ did not differ between males and females, smokers and nonsmokers, and between the tribes. Thus, 35 (2.6%) subjects with HbA₂ between 3.2 and 3.5% were at a risk of false negative diagnosis of BTT. Since iron deficiency and α⁺-thalassemia are both common and both lower HbA₂, modifications in screening recommendations for BTT are proposed.

Misdiagnosis of Hb D-Punjab/β-thalassemia is a potential pitfall in hemoglobinopathy screening programs: a case report

Compound heterozygosity for Hb D-Punjab [β121(GH4)Glu→Gln, GAA>CAA] /β-thalassemia (β-thal) must be carefully differentiated from homozygous Hb D-Punjab in premarital screening. This is essential when the partner is a carrier of β-thal trait. The case of a baby born affected with β-thal major (β-TM), from a marriage between a mother with β-thal trait and a father with Hb D-Punjab/β-thal, is presented. The father had been misdiagnozed as homozygous Hb D-Punjab during premarital screening, even though the screening program utilized complete blood counts and high performance liquid chromatography (HPLC). The factors that may have contributed to this midsiagnosis are presented and discussed. It is recommended that cases of Hb D-Punjab, or any other hemoglobin (Hb) variant appearing as homozygous, are carefully evaluated if microcytic hypochromic parameters not associated with α-thal are present. In all cases of suspected hemizygosis, molecular analysis should always be performed, and in particular if one partner is a β-thal carrier.

Beta-Thalassemia in Iran: new insight into the role of genetic admixture and migration

Iran with an area of 1.648 million km² is located between the Caspian Sea and the Persian Gulf. The Iranian population consists of multiethnic groups that have been influenced by various invasions and migration throughout history. Studies have revealed the presence of more than 47 different β-globin gene mutations responsible for β-Thalassemia in Iran. This paper is an attempt to study the origin of β-Thalassemia mutations in different parts of Iran. Distribution of β-Thalassemia mutations in Iran shows different patterns in different areas. β-Thalassemia mutations have been a reflection of people and area in correlation with migration and origin of ancestors. We compared the frequencies of β-globin mutations in different regions of Iran with those derived from neighboring countries. The analysis provided evidence of complementary information about the genetic admixture and migration of some mutations, as well as the remarkable genetic classification of the Iranian people and ethnic groups.

Epidemiological profile of common haemoglobinopathies in Arab countries

Haemoglobinopathies including the thalassemias and sickle cell disease are known to be prevalent inherited disorders in most Arab countries with varying prevalence rates and molecular characterisation. β-thalassemia is encountered in polymorphic frequencies in almost all Arab countries with carrier rates of 1-11 % and a varying number of mutations. The most widespread mutation in Lebanon, Egypt, Syria, Jordan, Tunisia and Algeria is the IVS-I-110 (G>A). In the Eastern Arabian Peninsula, the Asian Indian mutations (IVS-I-5 (G>C), codons 8/9 (+G) and IVS-I (-25 bp del)) are more common. The α-thalassemias are encountered in the majority of Arab countries in frequencies ranging from 1 to 58 % with the highest frequencies reported from Gulf countries. The (-α(3.7)) mutation is the most frequent followed by the non-deletional α2 polyadenylation signal mutation (AATAAA>AATAAG) and the α2 IVS1 5-bp deletion. The rates of sickle cell trait in Arab countries range from 0.3 to 30 %, with the Benin, the Arab-Indian and the Bantu haplotypes constituting the bulk of the haplotypes, leading to two major phenotypes; a mild one associated with the Arab-Indian and a severe one with the Benin and Bantu haplotypes. Public health approaches targeting prevention of haemoglobinopathies in Arab countries include newborn screening for sickle cell disease, and premarital screening for carriers of β-thalassemia and sickle cell disease. These services are still patchy and inadequate in many Arab countries recommending the upgrade of these services with strengthening of the education and training of health care providers and raising public awareness on the feasibility of prevention and care for haemoglobinopathies.

Molecular basis of β-thalassemia in the United Arab Emirates

In an attempt to define the prevalence of β-thalassemia (β-thal) in the United Arab Emirates (UAE), we have conducted molecular studies on nearly 2000 randomly-selected adult UAE nationals. The results demonstrated that the prevalence of β-globin gene defects in the UAE was 8.5%. Among these anomalies were β-thal mutations, abnormal hemoglobin (Hb) variants, e.g., Hb S, Hb D-Punjab, Hb O-Arab, Hb C and Hb E. The sickle gene (β(S) or Hb S) contributed significantly to the molecular epidemiology of the hemoglobinopathies in the UAE. In this article, Hb S and other abnormal Hbs are excluded as they are comprehensively described by other contributors in this current issue. The molecular characterization and mutational analyses of all β-thal patients were carried out using current molecular techniques including amplification refractory mutation system (ARMS), restriction enzyme analysis (REA), dot-blot hybridization, β-strip hybridization, allele-specific oligonucleotide (ASO), polymerase chain reaction (PCR), gap-PCR and DNA Sequencing. Most of these techniques are now virtually obsolete. Almost all molecular characterizations are currently performed through PCR followed by DNA sequencing using a fully automated ABI PRISM™ 3130 Genetic Analyzer. Our molecular studies showed that the majority of the β-thal mutations in the UAE are very severe; the most common allele was the IVS-I-5 (G>C). Although this allele is a β(+)-thal, its phenotype is very severe. All other mutations are also severe β(0)-thal. High frequency of moderate or severe β-thal mutations have implications in the wide spectrum of clinical manifestations seen in patients whose phenotypes vary from β-thal intermedia (β-TI) to severe transfusion-dependent β-thal major (β-TM). The molecular pathology of the β-thal patients demonstrated that a vast majority were homozygous. The most frequent homozygous mutation was the IVS-I-5(G>C)/IVS-I-5(G>C) (53.0%) followed by -25 bp del/-25 bp del (6.8%), codons 8/9(+G)/codons 8/9(+G) (2.8%) and codon 39(C>T)/codon 39(C>T) (2.4%). Four mutations accounted for 65.0% of the homozygous patient population. Remarkably, the two most prevalent mutations, IVS-I-5 and Hb S, accounted for 77% of all the homozygous β-thal patients from the UAE. We showed 13 discrete homozygosities in the UAE national patients in contrast to 23 homozygosities in the expatriate population. Since the number of homozygous mutations has a direct correlation with the degree of consanguinity, the data shown here corroborate the social tendency towards family planning. In fact, in the UAE, more than 50% of all marriages are between relatives and more than half of these are between first cousins.

A descriptive profile of β-thalassaemia mutations in India, Pakistan and Sri Lanka

Thalassaemia is a common and debilitating autosomal recessive disorder affecting many populations in South Asia. To date, efforts to create a regional profile of β-thalassaemia mutations have largely concentrated on the populations of India. The present study updates and expands an earlier profile of β-thalassaemia mutations in India, and incorporates comparable data from Pakistan and Sri Lanka. Despite limited data availability, clear patterns of historical and cultural population movements were observed relating to major β-thalassaemia mutations. The current regional mutation profiles of β-thalassaemia have been influenced by historical migrations into and from the Indian sub-continent, by the development and effects of Hindu, Buddhist, Muslim and Sikh religious traditions, and by the major mid-twentieth century population translocations that followed the Partition of India in 1947. Given the resultant genetic complexity revealed by the populations of India, Pakistan and Sri Lanka, to ensure optimum diagnostic efficiency and the delivery of appropriate care, it is important that screening and counselling programmes for β-thalassaemia mutations recognise the underlying patterns of population sub-division throughout the region.

Mutations of a country: a mutation review of single gene disorders in the United Arab Emirates (UAE)

The United Arab Emirates inhabitants are ethnically diverse, with ancestries from Arabia, Persia, Baluchistan, and Africa. However, the majority of the current five million inhabitants are expatriates from the Asian subcontinent, Middle Eastern, African, and European countries. Consanguineous marriages within most UAE subpopulations are still the norm, leading to the formation of isolates and higher frequencies of recessive conditions. The UAE is ranked sixth in terms of prevalence of birth defects, with more than 270 genetic disorders reported in the national population. The UAE has high frequencies of blood disorders including thalassemias, sickle cell disease, and G6PD. In addition, certain genetic conditions are relatively common including cystic fibrosis, Joubert, and Meckel syndromes. Furthermore, numerous rare congenital malformations and metabolic disorders have been reported. We review the single gene disorders that have been studied at the molecular level in the UAE (which currently stand at 76) and compile the mutations found. Several novel (p.S2439fs) mutations have been reported including c.7317delA in NF1, c.5C>T (p.A2V) in DKC1, c.1766T>A (p.I589N) in TP63, and c.2117G>T (p.R706L) in VLDLR. We hope that this review will form the basis to establish a UAE mutations database and serve as a model for the collection of mutations of a country.

Chromatographic analysis of Hb S for the diagnosis of various sickle cell disorders in Pakistan

Sickle cell disease remains a relatively obscure theme in research on haemoglobinopathies in Pakistan. Limited data is available regarding its prevalence in the country. The objective of our study was not only to estimate the frequency of different sickle cell diseases but also to provide quantitative estimation of haemoglobin S and other haemoglobin variants using an automated high-performance liquid chromatography (HPLC) system. For this purpose, we retrospectively evaluated the results of HPLC performed on all patients with suspected haemoglobinopathies during the years 2005 and 2006. Information derived from various sources was used to identify a particular genotype by analysing each sample containing Hb S with respect to haemoglobin, red cell indices and levels of various associated haemoglobin variants. Analysis of 15,699 samples identified 302 patients with Hb S (1.92%). The genotypes identified included Sbeta(0) (46.7%), SS (19.2%), SA (11.6%), Sbeta(+) (8.6%) and SD (2.3%). Thirty-five cases could not be categorised and were labelled 'unclassified'. Majority of the patients (62.3%) were below the age of 18 years. Balochistan, which is the largest province based on the area, yielded the highest number of patients (n = 140). In the Sbeta(0) group, the mean haemoglobin and Hb S were lower in children compared to adults (p value of 0.001 and 0.016, respectively). We conclude that sickle cell disorders are prevalent in Pakistan to a significant extent, being concentrated in certain areas of the country. We present the first report of various haemoglobin S genotypes from our population. It is hoped that it will act as a database to characterise the same for our population.

United Arab Emirates: communities and community genetics

The UAE society is cosmopolitan, but the indigenous inhabitants are traditional with puritanical values despite their exposure to other vastly different cultures and habits. Marriages between consanguineous couples are still the norm rather than the exception. As a result, there is a high frequency of genetic disorders, particularly autosomal recessive types. Despite the high frequency of genetic disorders like haemoglobinopathies and others characteristically found in this population, genetic services are inadequate. Screening for certain disorders like thalassaemia are not applied on a wide scale. Abortion is illegal, and therefore, prenatal diagnosis or preconception tests are not done. With the absence of a good national database, deficiency of genetic services and absence of preventative alternatives for carrier couples, genetic counsellors find it difficult to advice pragmatic solutions to issues relating to genetic diseases. This paper reviews common genetic problems in the UAE with special emphasis on available genetic services and support to families with children with inherited disorders. Existing barriers to the improvement of clinical services by prenatal counselling are also discussed.