New insights into thalassemia: Latest studies using Devyser Thalassemia for NGS testing

Next-generation sequencing (NGS) is enhancing our understanding of genetic disorders, including thalassemia. Recent studies demonstrate the effectiveness of Devyser Thalassemia in identifying a wide range of genetic mutations associated with thalassemia, providing detailed genetic profiles, and improving diagnostics. In this blogpost we highlight some of the fascinating research using Devyser Thalassemia. 

Atypical Interference in Hb A1c Measurements Might Be Due to Mosaic Expression of Hemoglobin Variants – Clinical Chemistry, 2024¹ 

Annelie Strålfors, Kristina Lagerstedt-Robinson, and Britta Landin 

This letter describes two cases of atypical hemoglobin (Hb) variants interfering with Hb A1c measurements, potentially affecting diabetes treatment: 

• Case 1: A 70-year-old woman had an unknown 20% Hb fraction. Massively parallel sequencing (MPS) identified an HBB variant (c.438T>A), corresponding to Hb McKees Rocks, in 17% of reads, undetectable by Sanger sequencing. 

• Case 2: A 49-year-old man showed a low Hb A1c level (3.8%) and a high labile A1c peak (23%). MPS confirmed the presence of Hb N-Timone (c.25A>G), detected in 16% of reads. 

MPS provided higher sensitivity and identified low-level mosaicism not detected by Sanger sequencing, highlighting the importance of recognizing mosaic Hb variants to avoid misdiagnosis and ensure appropriate treatment. 

Three Haemoglobin Variants for Congenital Erythrocytosis and Sickle Cell Disease HbSC – Biomedical Research & Environmental Sciences, 2022² 

Rita Testa Epifania, et al. 

This article presents three clinical cases of rare hemoglobinopathies in Italy, emphasizing the importance of accurate identification of rare thalassemia variants: 

• Case 1: A 68-year-old male with polyglobulia was treated unsuccessfully with phlebotomies. Diagnosed with Haemoglobin Regina after HPLC and genetic testing revealed a specific mutation (β 96 Leu > Val). 

• Cases 2 & 3: Two brothers, ages 57 and 58, with high hematocrit levels were diagnosed with Haemoglobin Trollhattan after testing revealed a mutation (β 20 Val > Glu). 

The study underscores the necessity of molecular genetic analysis for patients with high hematocrit levels when secondary causes are excluded, supporting the need for comprehensive genetic testing in diagnosing hemoglobinopathies. 

Application of Targeted Next-Generation Sequencing for the Investigation of Thalassemia in a Developing Country: A Single Center Experience – Diagnostics, 2023³ 

Razan Hayati Zulkeflee, et al. 

This study demonstrates the effectiveness of Devyser Thalassemia in identifying genetic variants missed by traditional methods: 

• The study identified various genetic variants missed by traditional methods such as multiplex-ARMS and GAP-PCR. 

• NGS detected additional mutations, including -50 G>A (HBB.-100G>A) and HBA2 mutations, namely CD 79 (HBA2.239C>G) and CD 142 (HBA2.427T>C). 

The research highlights the advantages of using targeted NGS over traditional methods for thalassemia diagnosis, particularly in developing countries with limited resources. The findings support the implementation of NGS in routine clinical practice to improve patient care and genetic counseling. 

Biallelic hypomorphic variants in CAD cause uridine-responsive macrocytic anemia with elevated haemoglobin-A2 – British Journal of Haematology, 2023⁴ 

Orna Steinberg-Shemer, et al. 

This study explores the genetic basis of macrocytic anemia linked to biallelic hypomorphic variants in the CAD gene: 

• Using NGS, researchers identified two CAD gene variants: p.Pro454Arg and p.Gly1290Ser. Despite functional assays suggesting these variants were non-pathogenic, clinical presentation indicated otherwise. 

• The patient exhibited macrocytic anemia with elevated haemoglobin-A2 levels and significant improvement with uridine supplementation. 

The study highlights the limitations of current functional assays and in silico prediction tools, suggesting CAD gene sequencing for patients with similar hematological phenotypes to ensure accurate diagnosis and treatment. 

Context Base Editing for Splice Correction of IVSI-110 β-Thalassemia – Molecular Therapy. Nucleic Acids, 2024⁵ 

Basma Naiisseh, et al. 

This article focuses on using adenine base editors (ABEs) to correct the IVSI-110 (G>A) splice mutation in β-thalassemia: 

• Researchers used adenine base editors (SpRY and SpG) to correct the IVSI-110 (G>A) splice mutation in patient-derived CD34+ cells, achieving up to 90% editing of critical sequence elements. 

• Post-editing, the cells showed significant improvements in hemoglobinization and erythropoiesis, with SpG7 demonstrating higher efficacy and safety than SpRY6. 

The study supports using ABEs as a safer, more efficient alternative to traditional genome-editing methods for treating β-thalassemia. 

Detection of 13 Novel Variants and Investigation of Mutation Distribution by Next Generation Sequencing in Hemoglobinopathies: A Single Center Experience – Indian Journal of Hematolofy & Blood Transfusion, 2023⁶ 

Ozge Ozalp and Ozlem Anlas 

This study examines the effectiveness of NGS in identifying genetic mutations in hemoglobinopathies: 

• The study identified 13 novel genetic variants using NGS, highlighting its ability to uncover mutations that traditional methods might miss. 

• Analysis provided insights into the distribution and frequency of these mutations among the patient cohort. 

The study explores the advantages of NGS over traditional methods in identifying genetic mutations in hemoglobinopathies. NGS offers a comprehensive, cost-effective approach for precise and early diagnosis, improving patient outcomes. 

Conclusion 

As we continue to explore and refine these technologies, the future of thalassemia research and treatment is promising. The insights gained from these studies raise the importance of adopting advanced genetic testing methods to stay at the forefront of medical research and patient care. 

 

 References

1. Strålfors A, Lagerstedt-Robinson K, Landin B. Atypical Interference in Hb A1c Measurements Might Be Due to Mosaic Expression of Hemoglobin Variants. Clin Chem. Published online July 3, 2024. doi:10.1093/clinchem/hvae091 

1. Rita Testa E, Geremia L, Brunetta V, et al. Three Haemoglobin Variants for Congenital Erythrocytosis and Sickle Cell Disease HbSC. Journal of Biomedical Research & Environmental Sciences. 2022;3(10):1204-1207. doi:10.37871/jbres1579 

1. Zulkeflee RH, Bahar R, Abdullah M, Mohd Radzi MAR, Md Fauzi A, Hassan R. Application of Targeted Next-Generation Sequencing for the Investigation of Thalassemia in a Developing Country: A Single Center Experience. Diagnostics (Basel). 2023;13(8):1379. Published 2023 Apr 10. doi:10.3390/diagnostics13081379 

1. Steinberg-Shemer O, Yacobovich J, Noy-Lotan S, et al. Biallelic hypomorphic variants in CAD cause uridine-responsive macrocytic anaemia with elevated haemoglobin-A2. Br J Haematol. 2024;204(3):1067-1071. doi:10.1111/bjh.19215 

1. Naiisseh B, Papasavva PL, Papaioannou NY, et al. Context base editing for splice correction of IVSI-110 β-thalassemia. Mol Ther Nucleic Acids. 2024;35(2):102183. Published 2024 Mar 30. doi:10.1016/j.omtn.2024.102183 

1. Ozalp O, Anlas O. Detection of 13 Novel Variants and Investigation of Mutation Distribution by Next Generation Sequencing in Hemoglobinopathies: A Single Center Experience. Indian J Hematol Blood Transfus. 2024;40(2):268-280. doi:10.1007/s12288-023-01694-7