Molecular Basis of β-Thalassemia Intermedia in Erbil Province of Iraqi Kurdistan

Magnitude of Bone Disease in Transfusion-Dependent and Non-Transfusion-Dependent β-Thalassemia Patients

Introduction β-Thalassemia is a common inherited disease in the northern part of Iraq. A considerable number of transfusion-dependent (TDT) and non-transfusion-dependent (NTDT) β-thalassemia patients suffer bone problems. The objective of this study was to evaluate the degree of bone disease in the TDT and NTDT patients using a dual-energy X-ray absorptiometry (DEXA) scan. Patients and methods In this study, 53 TDT and 20 NTDT patients aged ≥10 years were enrolled. Their bone status was assessed using the DEXA scan at the lumbar spine (L1-L4) and femoral neck. The effect of physical, biochemical, and hormonal characteristics on the bone mineral density (BMD) parameters was evaluated. The value of the BMD Z-score was the measure to decide on the magnitude of bone disease. Results and discussion The mean age of the enrolled patients was 24.1 years. The BMD Z-score values were significantly lower among the TDT patients at the lumbar spine and femoral neck (BMD Z-score: -2.05 and -1.51 versus -2.29 and -0.71; p=0.044 and 0.009, respectively). The proportion of osteoporosis at the lumbar spine was significantly higher in the TDT group than in the NTDT group (69.8% versus 40%; p <0.001). The BMD Z-score correlated significantly with patient BMI and parathyroid hormone (PTH) level in both the TDT and NTDT groups. No correlation was found with age, hemoglobin (Hb), and serum levels of calcium, vitamin D, ferritin, phosphorus, and alkaline phosphatase (ALP). Conclusions Impaired bone density was encountered at high proportions in our thalassemia patients. TDT patients suffered more severe bone disease than NTDT patients.

A Population-Oriented Genetic Scoring System to Predict Phenotype: A Pathway to Personalized Medicine in Iraqis With β-Thalassemia

To assess the roles of genetic modifiers in Iraqi β-thalassemia patients, and determine whether a genotype-based scoring system could be used to predict phenotype, a total of 224 Iraqi patients with molecularly characterized homozygous or compound heterozygous β-thalassemia were further investigated for α-thalassemia deletions as well as five polymorphisms namely: rs7482144 C > T at HBG2, rs1427407 G > T and rs10189857 A > G at BCL11A, and rs28384513 A > C and rs9399137 T > C at HMIP. The enrolled patients had a median age of 14 years, with 96 males and 128 females. They included 144 thalassemia major, and 80 thalassemia intermedia patients. Multivariate logistic regression analysis revealed that a model including sex and four of these genetic modifiers, namely: β+ alleles, HBG2 rs7482144, α-thalassemia deletions, and BCL11A rs1427407 could significantly predict phenotype (major versus intermedia) with an overall accuracy of 83.9%. Furthermore, a log odds genetic score based on these significant predictors had a highly significant area under curve of 0.917 (95% CI 0.882-0.953). This study underscores the notion that genetic scoring systems should be tailored to populations in question, since genetic modifiers (and/or their relative weight) vary between populations. The population-oriented genetic scoring system created by the current study to predict β-thalassemia phenotype among Iraqis may pave the way to personalized medicine in this patient's group.

Detection of a Rare Mutation in the Initiation Codon of the β-Globin Gene (HBB:C.2T > C; P.Met1Thr)

β-thalassemia is one of the most common inherited autosomal disorders in the northern Iraqi Kurdistan region. This study reports a rare mutation in the initiation codon of the β-globin gene (HBB: c.2T > C; p.Met1Thr) in an 11-year-old male with severe transfusion-dependent β-thalassemia. Molecular testing to uncover the mutations of the β-globin gene in the proband and his parents was performed by amplification and reverse hybridization. Sanger sequencing was conducted for further identification. A severe β-globin gene mutation in codon 8/9 [+G] was initially identified in the proband and his mother's DNA samples. However, the detection of only one β-globin gene mutation was not enough to elucidate the patient's severe phenotype. Thus, a rare mutation in the initiation codon was identified later in the proband and his father by Sanger sequencing. In thalassemias, the presence of a rare mutation should be suspected when the patient's genotype does not correlate with the phenotype.

Identification of novel mutations in β-thalassemia patients in Maysan Governorate, Iraq

BACKGROUND

In homozygous β-thalassemia, the primary genetic modifiers affecting the clinical severity of β-thalassemia are genetic variants and the ability to reduce globin chain imbalance, thus resulting in a milder form of thalassemia. However, there are few reports on the molecular genetics of β-thalassemia in Iraq.

METHODS

We performed PCR and DNA sequencing on 40 Iraqi patients who were clinically suspected of having β-thalassemia.

RESULTS

The first genetic sequencing study was conducted in Maysan Governate, Iraq, using patients from various locations to identify novel mutations. There were five novel mutations: 294.T>C 12% (city center and Almajar district), 205. C>T 25% (city center, Alsalam, and Almashrah districts), 289.G>A 38% (Almaymuna and Gleat Salih districts), 49.T>C 32% (city center), and 624.C>A 32% (city center). These mutations were identified among β-thalassemia patients by two regions of HBB gene 696 bp and 861 bp.

CONCLUSIONS

The discovery of new genetic variants helps predict the severity of β-thalassemia disease. There are relatively few studies in molecular genetics of β-thalassemia in Iraq, and the new mutations reported here will provide valuable data for the prevention and control of β-thalassemia in Maysan Governate, Iraq. The results can lead to new genetic sequencing investigations for other Iraqi regions.

Updated Molecular Spectrum of β-Thalassemia Mutations in Duhok Province, Northern Iraq: Ethnic Variation and the Impact of Immigration

Immigration impact on genetic epidemiology of thalassemia worldwide is well-recognized. Over the past decade, the Duhok Province of Northern Iraq attracted a large number of immigrants. To assess whether immigration had contributed to changes in the mutation spectrum of β-thalassemia (β-thal) in the region, we recruited 218 registered patients with symptomatic β-thal. The recruited patients included 50 (22.9%) from resettled migrant families. A total of 431 β-thal alleles were fully characterized, with 20 different thalassemia mutations, the most frequent being IVS-II-1 (G>A) (HBB: c.315 + 1G>A), IVS-I-6 (T>C) (HBB: c.92 + 6T>C), codon 5 (-CT) (HBB: c.17_18delCT), IVS-I-110 (G>A) (HBB: c.93-21G>A), codon 44 (-C) (HBB: c.135delC), codon 8 (-AA) (HBB: c.25_26delAA) and IVS-I-1 (G>A) (HBB: c.92 + 1G>A) constituting 72.8% of the total. Some differences in mutation spectrum were observed compared to earlier studies from this same province, the most notable of which were the higher frequencies of IVS-I-110 and codon 8. Interestingly, the highest proportions of alleles related to immigrants were encountered in these two allele groups. Ethnic variation was also documented, so that while Muslim Kurds had IVS-II-1, IVS-I-6, IVS-I-110, codon 5 and codon 44 as their most frequent mutations, the most frequent among Kurdish Yazidis, were codon 5, codon 44, codon 8 and IVS-I-6. These ethnic variations and changes in mutation spectrums are important and should be taken in consideration to ensure effective implementation of the thalassemia preventive program.

Molecular Characterization and Disease-Related Morbidities of β-Thalassemia Patients from the Northeastern Part of Iraq

BACKGROUND

β-thalassemia is a significant problem in the northeastern part of Iraq, and has imposed a huge burden on the health authorities.

OBJECTIVE

To identify the molecular characterization and morbidity prevalence in transfusion-dependent thalassemia (TDT) and non-transfusion dependent thalassemia (NTDT) phenotypes in northeastern Iraq.

PATIENTS AND METHODS

This is a cross-sectional study conducted on 242 β-thalassemia patients from 162 families. Reverse hybridization technique and direct gene sequencing were used to characterize β-thalassemia mutations, and medical records of the patients were reviewed with a well-designed questionnaire.

RESULTS

A total of 22 β-globin mutations arranged in 53 different genotypes were identified: IVS-II-1 (G> A) (35.7%), followed by IVS-I-6 (T> C) (18.0%), and codon 8/9 (+G) (8.5%) were the most frequent. Among disease-related morbidities, bone disease amounted to (66.9%), followed by endocrinopathies (32.2%), hepatobiliary complications (28.9%), and pulmonary hypertension (9.9%), whereas thrombosis, extramedullary hemopoiesis, and leg ulcers were less frequent.

CONCLUSION

The overall complications rate was 78.9%, with a growing probability of complications with advanced age, with evidently higher rates in patients with β0β0 and β0β+ genotypes that explain the role of underlying genetic defects in the pathophysiology of disease complications.

Genetic epidemiology of hemoglobinopathies among Iraqi Kurds

Hemoglobinopathies are major health problems among Iraqi Kurds, who are a distinct ethnic group inhabiting North and Northeastern Iraq. We reviewed published literature on these disorders in this part of the world, and it was revealed that the most prevalent is β-thalassemia with carrier rates of 3.7-6.9%. Alpha thalassemia is less prevalent with carrier rates of 0.03-1.22%, while the sickle cell gene is variably distributed with carrier rates of 0.06-1.2%. Other structural hemoglobinopathies and δβ-thalassemia are sporadic. Twenty-seven different β-thalassemia mutations were identified, with seven constituting 82% of 1039 chromosomes characterized, namely: IVS-II-1 (G>A), IVS-I-6 (T>C), IVS-I-I (G>A), codon 8 (-AA), codon 8/9 (+G), IVS-I-110 (G>A), and codon 5 (-CT). There were notable regional variations in the distribution of β-thalassemia mutations, with Cd44 being mainly prevalent in the North, while IVS-I-110 is mainly prevalent in the East. In relevance to α-thalassemia, ten different mutations were detected, with the four most frequent constituting 92.4% of 262 alleles characterized being: -α^3.7, --^MED, α^-5ntα, and α^PolyA1α. In relevance to sickle cell gene, it is seen in the northern part of the region bordering Turkey, with comparable prevalence rates, and is associated, similar to Turkey, mainly with the Benin haplotype, unlike that in Southern Iraq where it is associated with the Arab-Indian haplotype, similar to Eastern Arabian Peninsula. Given the high prevalence of hemoglobinopathies in the region, and the high rates of consanguineous marriages, a preventive program was initiated in 2008, and results of its first 5 years were promising, though there are still many outstanding challenges that require addressing.

Genotype-phenotype correlation of HbH disease in northern Iraq

BACKGROUND

HbH disease results from dysfunction of three, less commonly two, α-globin genes through various combinations of deletion and non-deletion mutations. Characterization of the mutations and the underlying genotypes is fundamental for proper screening and prevention of thalassaemia in any region. The aim of this study was to explore the genetic arrangements of HbH disease and to correlate the genotypes with the clinical phenotypes.

METHODS

A total of 44 HbH disease patients were enrolled in this study. They were clinically and haematologically assessed. The patients were tested for 21 common α-globin gene mutations using multiplex PCR and reverse hybridization. According to the genotype, the patients were categorized into two separate sub-groups, deletion and non-deletion types HbH disease.

RESULTS

Within the studied HbH disease patients, eight different α-globin gene mutations were detected in nine different genetic arrangements. The --^MED and -α^3.7 deletions were the two most frequently encountered mutations (37.5 and 35.2% respectively). Patients with deletion genotypes constituted 70.4%. The most common detected genotype was --^MED/-α^3.7 (59.1%), followed by α^poly-A1α/α^poly-A1α (13.6%). For the first time, coinheritance of two relatively mild mutations (-α^3.7/αα^Adana) was unpredictably detected in a 1.5 year-old child with Hb of 7.1 g/dL.

CONCLUSION

The HbH disease patients' clinical characteristics were variable with no ample difference between the deletion and non-deletion types. These results can be of benefit for the screening and management of thalassaemia in this region.

Molecular spectrum of α-thalassemia mutations in Erbil province of Iraqi Kurdistan

α-Thalassemia is a globally prevalent genetic disorder of hemoglobin (Hb) structure where the rate of α-globin chain synthesis is reduced or absent based on the underlying α-globin mutation(s). This study aimed to define the spectrum of α-globin gene mutations and assess their relative frequency within a group of α-thalassemia carriers. A total of 96 young subjects with unexplained hypochromia and microcytosis were recruited. They were referred from the premarital hemoglobinopathy screening and genetic counseling center in Erbil. All subjects were genetically tested for 21 common α-globin gene mutations using multiplex PCR and reverse hybridization. Six different α-globin gene mutations and nine different genotypes were detected in 84 carrier subjects. Their mean Hb was 12.9 (± 1.29) g/dL, of whom 49 subjects (58.3%) had a normal Hb level. The two most frequently encountered mutations were -α^3.7 deletion (62.86%) and α2^-5nt mutation (20%). Deletions were encountered in 71.43% of the mutated alleles. The most commonly observed genotype was -α^3.7/αα (46.43%), followed by -α^3.7/-α^3.7 and α^-5ntα/αα genotypes (10.72% each). Carriers of α^poly-A1α/αα and -α^3.7/-α^-5ntα genotypes showed significantly lower Hb, mean cell volume, and mean cell Hb values comparing to carriers of most other genotypes. In our population, the spectrum of α-globin mutations was confined to a limited number of mutations with deletions being mostly observed.

Beta-Thalassemia Intermedia: A Single Thalassemia Center Experience from Northeastern Iraq

OBJECTIVE

To determine the molecular characterization and disease-associated complications of beta-thalassemia intermedia (β-TI) patients in Sulaymaniyah province, northeastern Iraq.

METHODS

A total of 159 β-TI) patients in Sulaymaniyah province, northeastern Iraq. β-TI) patients in Sulaymaniyah province, northeastern Iraq.

RESULTS

Nineteen different β-globin gene mutations arranged in 37 various genotypes were determined. The most frequent were IVS-II-I (G>A) (47.2%), followed by IVS-I-6 (T>C) (23.3%) and IVS-I-110 (G>A) (5%). Among disease-related morbidities documented, bone disease amounted to 53% (facial deformity and osteoporosis), followed by endocrinopathies 17.6% (growth retardation and subclinical hypothyroidism), cholelithiasis 13.8%, pulmonary hypertension 11.3%, and abnormal liver function test 7.5%, whereas venous thrombosis, extramedullary hemopoiesis, and leg ulcer were less frequently observed. Age ≥ 35 and female sex were risk factors for cholelithiasis, while age was an independent risk for hypothyroidism and female sex was associated with increased risk for osteoporosis. Mean serum ferritin of ≥1000 μg/L was associated with an increased risk of osteoporosis, whereas chelation therapy was protective for a multitude of other complications. Transfusion, on the other hand, increased the risk of osteoporosis, yet it was protective for cholelithiasis and hypothyroidism. Moreover, splenectomy was protective for cholelithiasis, although it was an independent risk for hypothyroidism. Finally, hydroxyurea was associated with an increased risk of osteoporosis, while it was protective for cholelithiasis. Discussion and Conclusion. β +-thalassemia mutation had contributed to 41.25 of families with a less severe β-thalassemia phenotype in the northeastern part of Iraq, justifying the need to investigate the contribution of genetic modifiers in ameliorating disease severity. In addition, the substantial number of β-TI patients developed disease-related morbidities, which necessitates the need for more appropriate clinical management with earlier intervention.β-TI) patients in Sulaymaniyah province, northeastern Iraq. μg/L was associated with an increased risk of osteoporosis, whereas chelation therapy was protective for a multitude of other complications. Transfusion, on the other hand, increased the risk of osteoporosis, yet it was protective for cholelithiasis and hypothyroidism. Moreover, splenectomy was protective for cholelithiasis, although it was an independent risk for hypothyroidism. Finally, hydroxyurea was associated with an increased risk of osteoporosis, while it was protective for cholelithiasis. Discussion and Conclusion. β +-thalassemia mutation had contributed to 41.25 of families with a less severe β-thalassemia phenotype in the northeastern part of Iraq, justifying the need to investigate the contribution of genetic modifiers in ameliorating disease severity. In addition, the substantial number of β-TI patients developed disease-related morbidities, which necessitates the need for more appropriate clinical management with earlier intervention.Discussion and Conclusion. β +-thalassemia mutation had contributed to 41.25 of families with a less severe β-thalassemia phenotype in the northeastern part of Iraq, justifying the need to investigate the contribution of genetic modifiers in ameliorating disease severity. In addition, the substantial number of β-TI patients developed disease-related morbidities, which necessitates the need for more appropriate clinical management with earlier intervention.β-TI) patients in Sulaymaniyah province, northeastern Iraq. β-TI) patients in Sulaymaniyah province, northeastern Iraq.

HBG2 -158 (C>T) polymorphism and its contribution to fetal hemoglobin variability in Iraqi Kurds with beta-thalassemia minor

PURPOSE

Hemoglobin (Hb) F% is increased in up to half of beta-thalassemia (β-thal) carriers. Several polymorphisms have been linked to such variability in different populations, including HBG2 - 158(C>T) (Xmn I polymorphism) on chromosome 11. To determine the role of this polymorphism in such variability among Iraqi Kurds, the current study was initiated.

MATERIALS AND METHODS

A total of 102 consecutive patients diagnosed as β-thal minor were enrolled. The enrollees had their diagnosis based on peripheral blood counts and high-performance liquid chromatography to determine HbA2 and HbF. All enrollees had their DNA extracted by phenol-chloroform method and Xmn I polymorphism detected by restriction fragment length polymorphism-polymerase chain reaction.

RESULTS

The mean age (standard deviation [SD]) of the 102 enrollees was 25.4 (14.0) years, and the enrollees included 48 males and 54 females. Xmn I polymorphism was identified in heterozygous state in 46 (45.1%) patients and in homozygous state in one patient (0.98%). Thus, the minor allele frequency of this polymorphism was 0.235 in the studied group. There were no significant differences in red cell indices and HbA2% in carriers of the minor allele compared to noncarriers, while HbF% and absolute HbF concentrations were significantly higher in the former subgroup (P = 0.032 and 0.014, respectively). This polymorphism's contribution to HbF variability was found to be 5.8% in the studied sample. Furthermore, those with HbF ≥2% were 3.2 folds more likely to carry the minor allele.

CONCLUSIONS

Xmn I polymorphism is frequently encountered in Iraqi Kurds with β-thal minor, and it is significantly associated with higher fetal hemoglobin in these patients.

Association between genotype and disease complications in Egyptian patients with beta thalassemia: A Cross-sectional study

In beta thalassemia, the degree of globin chain imbalance is determined by the nature of the mutation of the β-gene. β° refers to the complete absence of production of β-globin on the affected allele. β⁺ refers to alleles with some residual production of β-globin. The homozygous state results in severe anemia that necessitates regular blood transfusion. On the other hand, frequent blood transfusion can lead to iron overload resulting in progressive dysfunction of the heart, Liver as well as multiple endocrinopathies. We studied the impact of genotype on the development of disease complications in patients with β thalassemia. A Cross sectional study was carried on 73 patients with beta thalassemia. Genotyping was determined by DNA sequencing technique. Routine investigations as well as MRI liver and heart were performed to assess iron overload. We found that β⁺β⁺ was the most common genotype in our patients followed by β°β° and β°β⁺. Mean Liver iron content (LIC) was significantly higher in β°β° compared to β°β⁺ and β⁺β⁺ genotypes and mean cardiac T2* was significantly lower in β°β° compared to β°β⁺ and β⁺β⁺ genotypes. Hepatic complications, hepatitis C, cardiac complications and some endocrinopathies were significantly higher in patients with β°β° genotype compared to other genotypes which explain the role of the underlying genetic defect in thalassemia patients in development of disease complications.

Impact of Genotype of Beta Globin Gene on Hepatic and Myocardial Iron Content in Egyptian Patients with Beta Thalassemia

Iron overload causes most of the mortality and morbidity associated with thalassemia. Excess iron deposits primarily in the liver, but once a threshold level is reached, iron loading may occur in other tissues such as the heart. Magnetic resonance imaging is a well established technique to noninvasively quantify myocardial and liver iron content. More than 300 disease-causing mutations have been identified. We aimed to determine the impact of genotype on liver iron content in patients with beta thalassemia. Cross sectional study was carried on 73 patients with beta thalassemia. MRI liver and heart was performed to determine hepatic and myocardial iron overload. Genotyping was determined by DNA sequencing technique. The mean liver iron content was 17.4 mg/g dw and mean cardiac T2* was 25.5 ms in our patients. Patients with β⁰β⁰ were associated with significantly higher liver and myocardial iron content compared to those with β⁰β⁺ and β⁺β⁺ genotypes. There was a clear association between genotype and both hepatic and myocardial iron overload. Patients with β⁰β⁰ had significantly higher liver and heart iron content compared to those with β⁰β⁺ and β⁺β⁺ genotypes. Liver iron content was strongly correlated to serum ferritin levels and myocardial iron overload.

β globin mutations in Turkish, Northern Iraqi and Albanian patients with β thalassemia major

The mutation detection of β thalassemia is absolutely necessary for molecular diagnosis, as well as any genetic epidemiological study. The β globin gene has 3 exons and 2 introns, involved in β-thalassemic pathogenesis. The study aim of the study is to characterize the spectrum of β globin gene mutations in 136 Turkish, Northern Iraqi and Albanian pediatric β thalassemia major patients. After genomic DNA extraction from venous blood and amplification of the target DNA regions with PCR, genotyping was achieved by Sanger based DNA sequencing. The IVSI-110 G>A mutation was the most frequent allele in the Turkish and Albanian patients. In Northern Iraqi patients IVSI-1 G>A was is the most frequent. There are two mutations are firstly reported for Albania [c.*111 A>G 3’ UTR (rs63751128) and c.113 G>A (p.Trp38Ter, p.W38*) (rs35887507)] with this study. These findings may be of value for genetic counseling, premarital diagnosis, prenatal diagnosis and prevention programs.

Molecular Characterization of β-Thalassemia Intermedia in Southeast Iran

Inheritance of mild mutations within the β-globin gene and coinheritance of α-thalassemia (α-thal) are known as two important genetic modifiers in β-thalassemia (β-thal) intermedia (β-TI). We aimed to evaluate the spectrum of β- and α-thal mutations in β-TI patients in Southeast Iran. Common β- and α-globin gene mutations were detected by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) and multiplex gap-PCR, respectively. There were 26 male (57.8%) and 19 female (42.2%) patients. HBB: c.92 + 5T > C [IVS-I-5 (G > C)] and HBB: c.-138C + 1G > A [IVS-II-I (G > A)] represented the prevalent alleles with respective frequencies of 60.0 and 10.0%. Other β-globin mutations included HBB: c.-138C > T [-88 (C > T)], HBB: c.27_28insG [frameshift codons (FSC) 8/9 (+G)], HBB: c.46delT [codon 15 (-T)], HBB: c.93-22_95del (IVS-I, 25 del), and the 619 bp deletion (NG_000007.3: g.71609_72227del619). The predominant genotypic combinations were β(0)/β(0) (68.9%), β(0)/β(+ )(8.9%) and β(+)/β(+ )(2.2%). Coinheritance of α-thal was observed in 33.0% of the patients, with the -α(3.7) (rightward) (NG_000006.1: g.34164_37967del3804) as the most common deletion (86.0%). One patient was diagnosed with the -α(4.2) (leftward) (AF221717) and one with the - -(MED) (g.24664_41064del16401) deletions, while no patients carried the -(α)(20.5) (g.15164_37864del22701), α(-5 nt) (HBA2: c.95 + 2_95_6delTGAGG) or codon 19 (-G) (HBA2: c.56delG) mutations. The alleviating molecular mechanism was not explainable by β(+ )or concurrent α-thal in more than half of our β-TI patients. This encourages conducting more studies to identify other contributing factors, especially Hb F-inducing genetic modifiers.