Gene spectrum analysis of thalassemia for people residing in northern China

Beta Thalassemia Carrier Rate: Problem Burden among High School Children

Background & Aim of the Work: β-Thalassemia (βT) is highly prevalent in some countries like Egypt. Accurate data about actual disease prevalence and heavily prevalent geographic locations are essential to help in early detection and in setting up effective preventive programs. We aim for screening βT carriers among Egyptian high school students in the Delta region.

SUBJECTS AND METHODS

A cross-sectional multicenter study was carried out on 4320 randomly selected students from four governorates of the Nile Delta region, Egypt. All patients were to be tested for their complete blood count. Those with microcytic hypochromic anemia not caused by iron deficiency were tested for βT carrier status using high-performance liquid chromatography.

RESULTS

The total prevalence of βT carrier rate was 6.13%. The highest prevalence was detected in Al-Sharkia Governorate, reaching 7.89%, followed by 6.90% in Al-Gharbia Governorate. Al- Dakahilia and Al-Menoufia showed lower rates of 4.86% and 3.73%, respectively.

CONCLUSION

Despite the premarital national screening program for βT in Egypt, the carrier rate is still high. More effort should be done into the proper implementation of national prevention programs.

Prevalence and molecular characterization of alpha and beta-Thalassemia mutations among Hakka people in southern China

Our aim was to investigate molecular features of thalassemia for proper clinical consultation and prevention in Heyuan. In our research, a total of 25,437 positive screening subjects were further subjected to a genetic analysis of α-thalassemia (α-thal) and β-thalassemia (β-thal). The deletion of α-thal mutation was tested by Gap-PCR, while the non-deletion of α-thal and β-thal mutation were identified by the PCR-reverse dot blot (PCR-RDB) technique. Nested PCR detected Hkαα/-- SEA and Hkαα/αα. Among the 25,437 positive screening subjects, 44.09% (11216/25437) subjects were bearers of thalassemia variations, and 30.85% (7847/25437) subjects showed α-thal changes alone. Among the 23 genotypes with α-thal mutation alone, the three common genotypes were --SEA/αα(68.34%), -α3.7/αα(16.44%), and -α4.2/αα(6.38%). Of the 11.50% (2924/25437) subjects and 29 genotypes with β-thal mutation alone, the three common genotypes were βCD41-42/βN(36.22%), βIVS-II-654/βN(30.88%), and β-28/βN(13.47%). Additionally, of the 1.75% (445/25437) subjects and 55 genotypes showed both α- and β-thal mutations. We also identified 269 cases of Hb H and six patients of Hkαα. Furthermore, the common genotypes of α-thal and β-thal mutations were consistent with allele frequencies of mutations. Our study establishes molecular features of thalassemia among Hakka people in Heyuan. It will be useful for developing strategies to prevent thalassemia.

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.

Genotypes of thalassemia in children: an analysis of 30 417 cases

OBJECTIVES

To investigate the distribution of genotypes of thalassemia in children in Guangxi, China.

METHODS

A total of 30 417 children with positive results of thalassemia screening in the Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region from January 2011 to December 2019 were enrolled. Single-tube multiplex PCR, agarose gel electrophoresis, and reverse dot blot hybridization technique were used for the detection of common α- and β-thalassemia genes. Gap-PCR or gene sequence analysis was performed for 2 703 children suspected of rare thalassemia.

RESULTS

Among the 30 417 children with positive results of thalassemia screening, 23 214 (76.32%) were diagnosed with thalassemia, and the detection rates of α-thalassemia, β-thalassemia, and α-thalassemia with β-thalassemia were 47.77%, 23.75%, and 4.80% respectively. A total of 13 types of α-thalassemia alleles (18 480 alleles in total) were detected, mainly --SEA (54.98%), including seven rare alleles, i.e., --THAI (0.43%), HKαα (0.02%), -α30 (0.01%), -α1.0 (0.01%), -α2.4 (0.01%), -α21.9 (0.01%), and HBA2:C272-279 del (0.01%). A total of 17 types of β-thalassemia alleles (9 168 alleles in total) were detected, mainly CD41-42 (47.79%), followed by CD17 (25.53%), including three rare alleles, i.e., IVS-II-5 (0.02%), IVS-I-2 (0.01%), and Gγ(Aγδβ)0 (0.01%). A total of 37 genotypes were detected in 14 531 children with α-thalassemia, among which the most common 6 genotypes were --SEA/αα (52.20%), -α3.7/αα (13.24%), αCSα/αα (7.52%), -α4.2 (6.06%), --SEA/-α3.7 (5.91%), and αWSα/αα (3.41%), accounting for 88.34%. A total of 49 genotypes were detected in 7 223 children with β-thalassemia, among which the most common 6 genotypes were CD41-42/βN (45.81%), CD17/βN (24.30%), IVS-II-654/βN (7.49%), -28/βN (5.62%), CD71-72/βN (4.42%), and CD26/βN (3.94%), accounting for 91.13%. A total of 137 genotypes were detected in 1 460 children with both α- and β-thalassemia, mainly --SEA/αα combined with CD41-42/βN (14.17%) and CD17/βN (8.35%). A total of 2 050 children were diagnosed with hemoglobin H disease (α0/α+), among whom 134 had β-thalassemia heterozygote and 12 had Bart hydrops fetalis syndrome (--SEA/--SEA); 355 children were diagnosed with β-thalassemia double heterozygote, and 128 were diagnosed with β-thalassemia homozygote, including 93 children with α-thalassemia.

CONCLUSIONS

There are diverse gene mutations and rich genotypes of thalassemia among children in Guangxi, and α-thalassemia is more common, with --SEA/αα as the major genotype. There is a high proportion of children with both α- and β-thalassemia, and there are relatively high incidence rates of β-thalassemia double heterozygote and homozygote (intermedia and major).

[Rare thalassemia caused by novel nucleotide variants in the globin gene: four case reports and literature review]

目的

分析4例少见地中海贫血（地贫）患者的DNA序列、临床表型，提高对地贫的认识。

方法

对2014年5月至2019年12月4例少见地贫患者的临床及DNA序列特征进行回顾性分析并复习相关文献。

结果

地贫基因常规检测显示，例1～3均未检测到常见的3种α株蛋白1/2（HBA1/A2）基因缺失及其3种点突变和16种β株蛋白（HBB）基因点突变，例4检测到αα^--SEA缺失。HBA1/A2和HBB基因全序列Sanger测序示：例1～4分别存在HBB:c.347C>A、HBB:c.1A>G、HBB:c.393T>G及HBA2:c.301-1G>A（IVS-II-142 G>A）突变。同时，例2的祖父、父亲和姑姑均为HBB:c.1A>G杂合突变。

结论

本研究发现了新的珠蛋白基因突变，HBB:c.347C>A、HBB:c.1A>G和HBB:c.393T>G以及HBA2:c.301-1 G>A（IVS-II-142 G>A）突变在中国地贫患者中为首次报道，HBB:c.393T>G突变为全球首次报道，丰富了地贫基因突变数据库。

Molecular basis and diagnosis of thalassemia

Thalassemia is characterized by the impaired synthesis of globin chains due to disease-causing variants in α- or β-globin genes. In this review, we provide an overview of the molecular basis underlying α- and β-thalassemia, and of the current technologies used to characterize these disease-causing variants for the diagnosis of thalassemia. Understanding these molecular basis and technologies will prove to be beneficial for the accurate diagnosis of thalassemia.