Genetic polymorphisms of HbE/beta thalassemia related to clinical presentation: implications for clinical diversity

Essential genetic modifiers and their measurable impact in a community-recruited population analysis for non-severe hemoglobin E/β-thalassemia prenatal genetic counseling

The study aimed to identify essential phenotype-modulating factors among the pre-existence of several important ones and clarify their measurable impact on the clinical severity of hemoglobin (Hb) E/β-thalassemia in a community-recruited population analysis. This prospective study was designed to compare modifiers between community- (less or no symptoms) and hospital-recruited individuals with Hb E/β-thalassemia. The formerly included couples previously assessed for prenatal thalassemia at-risk status at 42 community and 7 referral hospitals in Thailand through on-site investigations between June 2020 and December 2021. The control included Hb E/β-thalassemia patients undergoing transfusions. The Mahidol score classified disease severity. Beta-globin, α0-thalassemia (-SEA, -THAI), α+-thalassemia (-α3.7, -α4.2), Hb Constant Spring (αCS) alleles, rs766432 in BCL11A, rs9399137 in HBS1L-MYB, and rs7482144-XmnI were evaluated. Modifiers were compared between 102 community- and 104 hospital-recruited cases. Alleles of β+, -SEA, -α3.7, αCS, and a minor allele of rs9399137 were prevalent in the community and mild severity groups (p < 0.05). Multiple linear regression analysis associated modulating alleles with -4.299 (-SEA), -3.654 (β+), -3.065 (rs9399137, C/C), -2.888 (αCS), -2.623 (-α3.7), -2.361 (rs7482144, A/A), -1.258 (rs9399137, C/T), and -1.174 (rs7482144, A/G) severity score reductions (p < 0.05). Certain modifiers must be considered in routine prenatal genetic counseling for Hb E/β-thalassemia.

Spatial and Temporal Expression Characteristics of the HBB Gene Family in Six Different Pig Breeds

β-Thalassemia induces hemolytic anemia caused by mutations in the β-chain gene locus. As humans progress from embryo to adulthood, hemoglobin recombines twice. To test whether similar hemoglobin reassembly occurs in pigs, bioinformatics tools were used to predict the pig hemoglobin-encoding gene. We then systematically analyzed the expression patterns of the HBB gene family in three developmental stages (weaning, sexual maturity and physical maturity) of six different pig breeds (Landrace, Yorkshire, Wuzhishan, Songliao black, Meishan and Tibetan). The results showed that the new hemoglobin coding gene 'HBB-like' was found in pigs, while the HBG gene did not exist in pigs, indicating that human-like reassembly might not exist in pigs. The HBB and HBB-like genes shared highly similar amino acid sequences and gene sequences. The genes on the β-chain were highly similar between humans and pigs and the amino acid sequences of human and pig HBB genes at position 26 and positions 41-42 were identical. qPCR results showed that there were significant differences in the spatiotemporal expression patterns of the four genes (HBA, HBB, HBB-like and HBE) across breeds. Our results provide a foundation for follow-up studies assessing the relationship between the gene-encoding hemoglobin and β-thalassemia disease, as well as the construction of a gene-edited β-thalassemia miniature pig model to assess β-thalassemia treatments.

Genetic predictions of life expectancy in southern Thai patients with β0‑thalassemia/Hb E

The types of β-thalassemia mutations, α-thalassemia interactions, and Hb F-associated SNPs have been described in association with variable disease phenotypes. This study aimed to determine the updated spectrum of β-thalassemia mutations and evaluate the contribution of primary and secondary genetic modifiers and SNPs to disease severity, age at onset, and predicted life expectancy in southern Thai β-thalassemia patients. A total of 181 β-thalassemia patients were enrolled and 135 β⁰-thalassemia/Hb E patients without α-thalassemia interactions were divided into three categories according to disease severity, age at onset, and predicted life expectancy. A total of 16 β-thalassemia mutations were identified in this study, and the three most common β-thalassemia mutations accounted for 61.4% of all mutations. It was also found that the XmnI polymorphism and rs2071348 were associated with age at onset and the predicted life expectancy. More than 82% of β⁰-thalassemia/Hb E patients with CC genotype (XmnI) were 3 years old or younger at onset. Additionally, >90% of the higher predicted life expectancy in β⁰-thalassemia/Hb E patients had the T allele of XmnI. Therefore, genetic prediction for age at onset and life expectancy is beneficial and practical during prenatal diagnosis or newborn screening for better genetic counseling and optimal management.

Variation in Genotype and DNA Methylation Patterns Based on Alcohol Use and CVD in the Korean Genome and Epidemiology Study (KoGES)

Alcohol consumption can increase the risk of chronic diseases, such as myocardial infarction, coronary artery disease, hyperlipidemia, and hypertension. We aimed to assess the association between genotype, DNA methylation patterns, alcohol consumption, and chronic diseases in Korean population. We analyzed 8840 subjects for genotypes and 446 for DNA methylation among the 9351 subjects from the Korean Genome and Epidemiology Study (KoGES). We further divided both groups into two sub-groups according to the presence/absence of chronic diseases. We selected genes whose methylation varied significantly with alcohol consumption, and visualized genotype and DNA methylation patterns specific to each group. Genome-wide association study (GWAS) revealed single nucleotide polymorphisms (SNPs) rs2074356 and rs11066280 in HECT domain E3 ubiquitin protein ligase 4 (HECTD4) to be significantly associated with alcohol consumption in both the presence. The rs12229654 genotype also displayed significantly different patterns with alcohol consumption. Furthermore, we retrieved differentially methylated regions (DMRs) from four groups based on sex and chronic diseases and compared them by drinking status. In genotype analysis, cardiovascular diseases (CVDs) showed a higher proportion in drinker than in non-drinker, but not in DMR analysis. Additionally, we analyzed the enriched Gene Ontology terms and Kyoto Gene and Genome Encyclopedia (KEGG) pathways and visualized the network, heatmap, and upset plot. We show that the pattern of DNA methylation associated with CVD is strongly influenced by alcoholism. Overall, this study identified genetic and epigenetic variants influenced by alcohol consumption and chronic diseases.

The Prevalence of HBB Mutations among the Transfusion-Dependent and Non Transfusion-Dependent Hb E/β-Thalassemia Children in a Tertiary Center of West Bengal, India

Hb E (HBB: c.79G>A)/β-thalassemia (Hb E/β-thal) is responsible for nearly half of all the different kinds of severe β-thal. This disorder is characterized by a wide range of clinical variability ranging from mild, asymptomatic non transfusion-dependent thalassemia (NTDT) to severe transfusion-dependent thalassemia (TDT). The aim of the present study was to determine the prevalence of different β-globin gene (HBB) mutations in Hb E/β-thal subjects and their potential role in transfusion dependence. One hundred and ten consecutive children with Hb E/β-thal attending the Pediatric Department of Burdwan Medical College, Burdwan, West Bengal, India were enrolled. Based on hemoglobin (Hb) electrophoresis or high-performance liquid chromatography (HPLC), patients were recruited and later β-globin gene sequencing was done to find out the prevalence of different HBB mutations. Transfusion-dependent thalassemia was seen in 42 children (38.2%), while NTDT was seen in 68 children (61.8%). A total of 10 different β-globin mutant alleles were characterized. The most frequent mutation on the β-globin gene was IVS-I-5 (G>C) (HBB: c0.92+5G>C) in both groups. The β-globin gene mutations alone cannot determine transfusion dependence among the Hb E/β-thal patients.