RETROSPECTIVE ANALYSIS OF ALPHA GLOBIN COPY NUMBER VARIATIONS DETERMINED BY MLPA IN THE TRAKYA REGION

Year 2021, Volume: 84 Issue: 3, 348 - 353, 31.07.2021

Selma Demir , Hakan Gurkan , Damla Eker , Sinem Yalçıntepe , Emine İkbal Atlı , Engin Atlı

https://doi.org/10.26650/IUITFD.2021.880592

Abstract

Objective: Alpha thalassemia is a common type of hemoglobinopathy that occurs as a result of deletions or point mutations in the alpha globin gene cluster. The molecular analysis of alpha thalassemia is challenging due to the presence of genes with high sequence similarities in alpha globin gene clusters and pseudogenes. As well as in all genetic diseases, determining the causative mutation types of alpha thalassemia and their frequencies have critical importance for accurate genetic screening and prevention strategies. Material and Method: In our study, alpha globin copy number variations determined by the Multiplex Ligation-dependent Probe Amplifcation (MLPA) method were examined retrospectively with suspicion of alpha thalassemia in 35 female and 43 male patients tested in the Genetic Diseases Diagnosis Center of the Medical Genetics Department at Trakya University Faculty of Medicine. Results: The most common deletion among our patients was the −α3.7 (35.3%), followed by the -α20.5 (10.3%) deletion. The -αSEA deletion was detected in three patients while 4 out of 78 cases were found to have the -αMED deletion. In three patients, a heterozygous large deletion and in one case HS40 regulatory region deletion were detected. In 14 (18%) of the patients, α globin triplications were detected. The -α4.2 deletion was detected in only one of our patients. Conclusion: Our study is the first to report the presence of eight different alpha globin copy number changes and 13 different alpha globin genotypes in the Trakya region.

Keywords

Alpha thalassemia, globin, copy number variation

TRAKYA BÖLGESİNDE MLPA İLE BELİRLENEN ALFA GLOBİN KOPYA SAYISI DEĞİŞİKLİKLERİNİN RETROSPEKTİF ANALİZİ

Abstract

Amaç: Alfa talasemi, alfa globin gen kümesindeki delesyonların veya nokta mutasyonlarının bir sonucu olarak ortaya çıkan yaygın bir hemoglobinopati türüdür. Alfa talaseminin moleküler analizi, alfa globin gen kümesinde yüksek dizi benzerliklerine sahip genlerin ve psödogenlerin varlığı nedeniyle zordur. Tüm genetik hastalıklarda olduğu gibi, alfa talasemide de, altta yatan mutasyon türlerinin ve sıklıklarının belirlenmesi, doğru genetik tarama ve önleme stratejileri için kritik öneme sahiptir. Gereç ve Yöntem: Çalışmamızda, alfa talasemi şüphesiyle Trakya Üniversitesi Tıp Fakültesi Tıbbi Genetik Anabilim Dalı Genetik Hastalıklar Tanı ve Değerlendirme Merkezinde test edilen 35 kadın ve 43 erkek hastada Multipleks Ligasyon-bağımlı Prob Amplifikasyon (MLPA) yöntemiyle belirlenen alfa globin kopya sayısı varyasyonları geriye dönük olarak incelendi. Bulgular: Olgularımız arasında en sık (%35,3) saptanan delesyon −α3.7 ve ardından %10,3 görülme sıklığı ile −α20.5 delesyonu gelmekteydi. Üç olguda tüm probları kapsayan büyük delesyon, bir olguda ise HS40 düzenleyici bölgesinde delesyon saptanırken, 78 olgunun 4’ünde –αMED, üçünde ise –αSEA delesyonu saptandı. Olguların 14’ünde (%18) α globin triplikasyonları belirlendi. −α4.2 delesyonu olgularımızdan yalnızca bir tanesinde saptandı. Sonuç: Çalışmamız, Trakya bölgesinde sekiz farklı alfa globin kopya sayısı değişikliği ve 13 farklı alfa globin genotipinin varlığını bildiren ilk çalışmadır.

Keywords

Alfa talasemi, globin, kopya sayısı değişikliği

References

• 1. Harteveld CL, Higgs DR. Alpha-thalassaemia. Orphanet J Rare Dis 2010;5:13. [CrossRef]
• 2. Patrinos GP, Kollia P, Papadakis MN. Molecular diagnosis of inherited disorders: lessons from hemoglobinopathies. Hum Mutat 2005;26(5):399-412. [CrossRef]
• 3. Farashi S, Harteveld CL. Molecular basis of α-thalassemia. Blood Cells Mol Dis 2018;70:43-53. [CrossRef]
• 4. Onay H, Aykut A, Karaca E, Durmaz A, Solmaz AE, Çoğulu Ö, et al. Molecular spectrum of α-globin gene mutations in the Aegean region of Turkey: first observation of three α-globin gene mutations in the Turkish population. Int J Hematol 2015;102(1):1-6. [CrossRef]
• 5. Canatan D, Oğuz N, Güvendik I, Yıldırım S. The Incidence of Alpha-Thalassemia in Antalya-Turkey. Turk J Haematol 2002;19:433-4.
• 6. Cürük MA, Hb H. (beta4) disease in Cukurova, Southern Turkey. Hemoglobin 2007;31:265-71. [CrossRef]
• 7. Basak AN. The molecular pathology of beta-thalassemia in Turkey: the Bogaziçi University experience. Hemoglobin 2007;31:233-41. [CrossRef]
• 8. Acemoglu H, Beyhun NE, Vancelik S, Polat H, Guraksin A. Thalassaemia screening in a non-prevalent region of a pre- valent country (Turkey): is it necessary? Public Health 2008;122(6):620-4. [CrossRef]
• 9. Guvenc B, Yildiz SM, Tekinturhan F, Dincer S, Akyuzluer I, Okten S, et al. Molecular characterization of alpha- Thalassemia in Adana, Turkey: A single center study. Acta Haematol 2010;123(4):197-200. [CrossRef]
• 10. Celik MM, Gunesacar R, Oktay G, Duran GG, Kaya H. Spectrum of α-thalassemia mutations including first observation of H.–(FIL) deletion in Hatay Province, Turkey Blood Cells Mol Dis 2013;51(1):27-30. [CrossRef]
• 11. Karakaş Z, Koç B, Temurhan S, Elgün T, Karaman S, Asker G, et al. Evaluation of Alpha-Thalassemia Mutations in Cases with Hypochromic Microcytic Anemia: The İstanbul Perspective. Turk J Haematol 2015;32(4):344-50. [CrossRef]
• 12. Ünal S, Oktay G, Acıpayam C, İlhan G, Gali E, Celkan T, et al. Hemoglobin H Disease in Turkey: Experience from Eight Centers. Turk J Haematol 2016;5;33(1):56-9. [CrossRef]
• 13. Yuregir OO, Ayaz A, Yalcintepe S, Canbek S, Acik DY, Yilmaz BT, et al. Detection of α-Thalassemia by Using Multiplex Ligation-Dependent Probe Amplification as an Additional Method for Rare Mutations in Southern Turkey. Indian J Hematol Blood Transfus 2016;32(4):454-59. [CrossRef]
• 14. Ihaka R, Gentleman R. R: a language for data analysis and graphics. J Comput Graph Stat 1996;5:299-314. [CrossRef]
• 15. Akhavan-Niaki H, Youssefi Kamangari R, Banihashemi A, Kholghi Oskooei V, Azizi M, Tamaddoni A, et al. Hematologic features of alpha thalassemia carriers. Int J Mol Cell Med 2012;1(3):162-7.
• 16. Velasco-Rodríguez D, Blas C, Alonso-Domínguez JM, Vega G, Soto C, García-Raso A, et al. Cut-Off Values of Hematologic Parameters to Predict the Number of Alpha Genes Deleted in Subjects with Deletional Alpha Thalassemia. Int J Mol Sci 2017;13;18(12):2707. [CrossRef]
• 17. Wu MY, Zhou JY, Li J, Li DZ. The Frequency of α-Globin Gene Triplication in a Southern Chinese Population. Indian J Hematol Blood Transfus 2016;32(Suppl 1):320-22. [CrossRef]
• 18. Ma SK, Au WY, Chan AY, Chan LC. Clinical phenotype of triplicated alpha-globin genes and heterozygosity for beta0-thalassemia in Chinese subjects. Int J Mol Med 2001;8(2):171-5. [CrossRef]
• 19. Moosavi SF, Amirian A, Zarbakhsh B, Kordafshari A, Mirzahoseini H, Zeinali S, et al. The carrier frequency of α-globin gene triplication in an Iranian population with normal or borderline hematological parameters. Hemoglobin 2011;35(4):323-30. [CrossRef]
• 20. Guvenc B, Canataroglu A, Unsal C, Yildiz SM, Turhan FT, Bozdogan ST, et al. α-globin chain abnormalities with coexisting α-thalassemia mutations. Arch Med Sci 2012;8(4):644-9. [CrossRef]
• 21. Farashi S, Bayat N, Faramarzi Garous N, Ashki M, Montajabi Niat M, Vakili S, et al. Interaction of an α-Globin Gene Triplication with α-Globin Gene Mutations in Iranian Patients with α-Thalassemia Intermedia. Hemoglobin 2015;39(3):201-6. [CrossRef]
• 22. Coelho A, Picanço I, Seuanes F, Seixas MT, Faustino P. Novel large deletions in the human alpha-globin gene cluster: Clarifying the HS-40 long-range regulatory role in the native chromosome environment. Blood Cells Mol Dis 2010;15;45(2):147-53. [CrossRef]
• 23. Luo S, Chen X, Zhong Q, Wang Q, Xu Z, Qin L, et al. Analysis of rare thalassemia caused by HS-40 regulatory site deletion. Hematology 2020;25(1):286-291. [CrossRef]
• 24. Suemasu CN, Kimura EM, Oliveira DM, Bezerra MA, Araújo AS, Costa FF, et al. Characterization of alpha thalassemic genotypes by multiplex ligation-dependent probe amplification in the Brazilian population. Braz J Med Biol Res 2011;44(1):16-22. [CrossRef]
• 25. Colosimo A, Gatta V, Guida V, Leodori E, Foglietta E, Rinaldi S, et al. Application of MLPA assay to characterize unsolved α-globin gene rearrangements. Blood Cells Mol Dis 2011;15;46(2):139-44. [CrossRef]a