Genetics of Iranian Alpha-Thalassemia Patients: A Comprehensive Original Study

Support Vector Machine-Based Formula for Detecting Suspected α Thalassemia Carriers: A Path toward Universal Screening

The blood counts of α thalassemia carriers (α-thal) are similar to those of β thalassemia carriers, except for Hemoglobin A2 (Hb A2), which is not elevated. The objective of this study was to determine whether mathematical formulas are effective for detecting suspected α-thal. The data were obtained from the database of the prevention program for detecting couples at risk for having a child with hemoglobinopathy. Red Blood Cells (RBC) indices were analyzed using mathematical formulas, and the sensitivity and negative predictive value (NPV) were calculated. Among 1334 blood counts suspected of α-thal analyzed, only the Shine and Lal and the Support Vector Machine formulas revealed high sensitivity and NPV. Sensitivity was 85.54 and 99.33%, and NPV was 98.93 and 99.93%, respectively. Molecular defects were found in 291, and 81 had normal α genes. Molecular analysis was not performed in 962 of the samples. Based on these results, mathematical formulas incorporating one of these reliable formulas for detecting suspected α or β thalassemia carriers in the program of the automatic analyzers can flag these results, increase the awareness of the primary physicians about the carrier risk, and send an alert with a recommendation for further testing.

CRISPR Gene Therapy: A Promising One-Time Therapeutic Approach for Transfusion-Dependent β-Thalassemia—CRISPR-Cas9 Gene Editing for β-Thalassemia

β-Thalassemia is an inherited hematological disorder that results from genetic changes in the β-globin gene, leading to the reduced or absent synthesis of β-globin. For several decades, the only curative treatment option for β-thalassemia has been allogeneic hematopoietic cell transplantation (allo-HCT). Nonetheless, rapid progress in genome modification technologies holds great potential for treating this disease and will soon change the current standard of care for β-thalassemia. For instance, the emergence of the CRISPR/Cas9 genome editing platform has opened the door for precision gene editing and can serve as an effective molecular treatment for a multitude of genetic diseases. Investigational studies were carried out to treat β-thalassemia patients utilizing CRISPR-based CTX001 therapy targeting the fetal hemoglobin silencer BCL11A to restore γ-globin expression in place of deficient β-globin. The results of recently carried out clinical trials provide hope of CTX001 being a promising one-time therapeutic option to treat β-hemoglobinopathies. This review provides an insight into the key scientific steps that led to the development and application of novel CRISPR/Cas9–based gene therapies as a promising therapeutic platform for transfusion-dependent β-thalassemia (TDT). Despite the resulting ethical, moral, and social challenges, CRISPR provides an excellent treatment option against hemoglobin-associated genetic diseases.

The worldwide molecular spectrum and distribution of thalassaemia: a systematic review

CONTEXT

Thalassaemia is one of the most common inherited autosomal recessive disorders around the world. A considerable amount of literature has been published about the type of mutations and the prevalence of thalassaemia, but findings are often contradictory.

OBJECTIVE

This systematic review aimed to provide a comprehensive view of the prevalence of thalassaemia-associated mutations in different countries, their effect on haemoglobin (Hb) levels, as well as reporting thalassaemia-associated rare mutations.

METHODS

A systematic search of the literature was carried out through major indexing databases (MEDLINE/PubMed, Scopus, EMBASE, Cochrane central, and ISI web of science) using keywords: "Co-inheritance, αα, β, thalassaemia" and "α-β thalassaemia, Mediterranean anemia, mutations" from 1998-September 2019. Hand-searching was also performed. There was no language restriction.

RESULTS

The initial searches yielded 1059 studies, of which 92 articles were included following inclusion and exclusion criteria. Of these, 3.3% (3) of articles were cohort studies, and 96.7% (89) of the remaining articles were cross-sectional studies. Our findings showed that 45.6% (42) of researchers investigated β-thalassaemia, 22.9% (21) αα-β thalassaemia, and 31.5% (29) α thalassaemia.

CONCLUSION

The present study provides valuable information about the spectrum of thalassaemia-associated mutations, which can be useful for preventing thalassaemia, reducing costs of care, reducing the treatment-related side effects, and showing the most defective mutations.HighlightEvaluating the increase or decrease in the birth prevalence of thalassaemiaIdentifying the most common and rare mutations in various parts of the worldComparing researchers' findings from various parts of the world.

Molecular Genetic Analysis of α-Thalassemia in Hamadan Province, West Iran

Identifying couples who are carriers of thalassemia-causing mutations, followed by prenatal diagnosis (PND), is undoubtedly an effective way to prevent the birth of children with the disease. Our aim in this study was to report for the first time the spectrum of α-globin gene mutations in the population living in Hamadan Province, West Iran. Multiplex gap-polymerase chain reaction (gap-PCR), amplification refractory mutation system (ARMS)-PCR, and direct DNA sequencing of HBA1 and HBA2 genes were used to identify the α-thalassemia (α-thal)-causing mutations in a cohort of 389 individuals including 328 α-thal carriers and 61 normal subjects. A total of 17 different mutations and 25 different genotypes were detected. The -α^3.7 (rightward) deletion (NG_000006.1: g.34164_37967del3804) was the most frequent mutation, accounting for more than half of all mutations (61.04%). This study revealed that there is a variety of α-thal mutations and α-thal genotypes in Hamadan Province, West Iran. This observation is probably due to the complexity of the Hamadan Province population that is composed of Persians (Fars), Turks, Kurds, and Lurs/Laks. In conclusion, our results demonstrated the spectrum of mutations in α-globin genes in Iran and increased our understanding of their distribution in this country.

Fertility and pregnancy in Iranian thalassemia patients: An update on transfusion complications

BACKGROUND

Despite the significant advances in thalassemia pathobiology and efficacy of chelation regimens, complications of transfusion therapy have attenuated the reproductive health of thalassemia patients. Depending on clinical profiles, we aimed to assess the fertility status and stresses among thalassemia patients who desired to have children.

MATERIAL AND METHODS

A total of 213 couples in reproductive ages were enrolled in this study in Tehran. Patients' demographic, clinical, fertility and spouse's health status were documented. We evaluated the pituitary-gonadal axis, serum ferritin, liver enzymes, and alloimmunization before planning a pregnancy and reported them as a function of spontaneous conception and transfusion dependency.

RESULTS

Data showed that 131 patients (62%) had 228 spontaneous pregnancies leading to 198 (86.6%) successful pregnancies. A significant difference was observed in spontaneous pregnancy with respect to fertility complications and transfusion dependency. In addition, the clinical conditions of spouses in patients with any spontaneous pregnancy were more thalassemia carriers (P < .05). Moreover, serum ferritin levels had a significant negative correlation with the levels of Testosterone, Estradiol, luteinizing hormone, and follicle-stimulating hormone. Furthermore, a significant positive correlation was reported with the level of liver enzymes. Finally, alanine transaminase and aspartate transaminase had a significant negative correlation with pituitary hormones.

CONCLUSION

We suggest that organised instruction in addition to good iron chelation, especially during the puberty period, would reduce the oxidative damage and related complications in thalassemia patients. Moreover, infertility seems to be attributed to iron deposition in various endocrine organs, pituitary, reproductive system and the liver, contributing to hormonal metabolism.

The Spectrum of α-Thalassemia Mutations in Kurdistan Province, West Iran

In order to identify the α-thalassemia (α-thal) mutation spectrum in Kurdistan Province, West Iran, a total of 217 individuals, including 154 α-thal carriers and 63 normal subjects were investigated in this study. Molecular analysis of α1- and α2-globin genes using multiplex gap-polymerase chain reaction (gap-PCR), amplification refractory mutation system (ARMS)-PCR or direct DNA sequencing, showed 11 different α-globin variants. The -α^3.7 (rightward) deletion (NG_000006.1: g.34164_37967del3804) (70.32%), polyadenylation signal (polyA2) site (AATAAA>AATGAA) (α^polyA2α) (HBA2: c.*92A>G) (7.74%), -α^4.2 (leftward) deletion (6.45%) and codon 59 (or Hb Adana) (G>A) (αα^{codon 59}) (HBA1: c.179G>A) (4.52%) were the most frequent mutations in the present study. In conclusion, the spectrum of α-thal mutations in Kurdistan Province is closest to that in western provinces of Iran (Kurdish and Laki populations). In addition, it was revealed that the codon 59 mutation is common in the Kurdish population. On the other hand, despite the same ethnic background of Kurds in Iran and Iraq, the - -^{MED I} double gene deletion and polyA2 point mutation have different distributions in these two populations. Therefore, further studies are needed to identify the cause of these differences.

α-Thalassemia Mutations in Ilam Province, West Iran

Despite several studies performed in different provinces of Iran to identify the spectrum of α-globin gene mutations, no such study has so far been carried out in Ilam Province. A total of 274 individuals, including 201 α-thalassemia (α-thal) carriers and 73 normal subjects, originating from the northern counties of Ilam Province, participated in this study. Analysis of α-globin defects was performed using multiplex gap-polymerase chain reaction (gap-PCR), amplification refractory mutation system (ARMS)-PCR and direct sequencing, which revealed a total of 11 different mutations and 22 different genotypes. The -α^3.7 (rightward) (NG_000006.1: g.34164_37967del3804), α^-5 ntα (HBA2: c.95 + 2_95 + 6delTGAGG), and -α^4.2 (leftward) deletions were the most prevalent mutations identified in our study, with frequencies of 66.23, 10.09 and 8.33%, respectively. In conclusion, the present study showed that the α-thal mutation spectrum in Ilam Province, at least in the northern part of the province, is different from that in other geographical regions of Iran. These results increase our knowledge about the spectrum and distribution of α-globin gene mutations in Iran.

The Spectrum of α-Thalassemia Mutations in the Lak Population of Iran

α-Thalassemia (α-thal) is one of the most common genetic disorders worldwide. The aim of this study was to investigate for the first time the α-thal mutation spectrum in the Lak population living in Lorestan Province, Iran. One hundred and seventy-six α-thal carriers participated in the study. Multiplex gap-polymerase chain reaction (gap-PCR), amplification refractory mutation system (ARMS)-PCR and direct sequencing were used for the detection of different mutations on the α-globin (HBA1 and HBA2) genes. A total of 11 different mutations was identified. The -α^3.7 (rightward; NG_000006.1: g.34164_37967del3804) deletion was observed most frequently (56.35%), followed by α^-5 ntα (HBA2: c.95+2_95+6delTGAGG), α^polyA2α (HBA2: c.*92A>G) and - -^{MED I} (NG_000006.1: g.24664_41064del16401), with frequencies of 15.47, 9.39, and 6.08%, respectively. These four mutations accounted for more than 87.0% of the total mutated alleles. Moreover, 19 different genotypes were identified. The types and distribution pattern of the mutations identified in this study, in comparison with other studies conducted in Iran, was most similar to the Kurdish population of Kermanshah Province, Iran. Due to the lack of information on α-thal in Lorestan Province, it was not possible to compare the mutation spectrum in the Lur and Lak populations. In conclusion, our results may help in setting up a strategy for an α-thal screening program and genetic counseling in the Lak people.