Minor beta thalassemia masked by a hemoglobin A2 mutant`

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Published Sep 1, 2010
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Vol. 88 No. 9 (2010): Issue Sep 2010

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souheil Omar
Mohamed Bassem Hammami
Sameh Hadj-Taeib
Moncef Feki
Salem Abbes
Naziha Kaabachi

Abstract

Background: The elevation of hemoglobin A2 (HbA2) is an essential criterion in the diagnosis of minor ß thalassemia.
Aim: To report a case of minor ß thalassemia HbA2 with normal HbA2 rate.
Observation: We report the case of ten years old boy, with hypochromic microcytic anemia, refractory to iron treatment. The study of hemoglobin (Hb) has revealed the presence of a minor abnormal fraction of Hb, amounted to 2.8%, associated with the presence of HbF and normal levels of HbA2. Family study revealed the presence of two Hb abnormalities (ß thalassemia trait and HbA2 mutant) transmitted to offspring in isolation or associated. The genotypic study confirmed the presence of minor ‚0 thalassemia and a ‰ gene mutation, causing a new mutant HbA2 named HbA2 Pasteur-Tunis [‰59(E3)LysgAsn(AAGgAAC)].
Conclusion: The presence of ‰ mutant reduces HbA2 level and could hide ß thalassemia trait. Rigorous and methodical interpretation of phenotypic data is crucial to not overlook the presence of ß thalassemia trait, whose diagnosis is crucial for genetic counseling and prenatal diagnosis.

Keywords:

Anemia, ß thalassemia, hemoglobin, hemoglobin mutant

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References

  1. Chouk I, Daoud BB, Mellouli F, et al. Contribution to the description of the beta-thalassemia spectrum in Tunisia and the origin of mutation diversity. Hemoglobin 2004;28:189-95.
  2. North ML. Les anomalies de l'hémoglobine. Leur diagnostic en Biologie clinique. Ann Biol Clin (Paris) 1981;39:205-11.
  3. Zorai A, Harteveld CL, Bakir A, et al. Molecular spectrum of alphathalassemia in Tunisia: epidemiology and detection at birth. Hemoglobin 2002;26:353-62.
  4. Zorai A, Abbes S, Préhu C, et al. Hb H disease among Tunisians: molecular characterization of alpha-thalassemia determinants and hematological findings. Hemoglobin 2003;27:57-61.
  5. Fattoum S, Messaoud T, Bibi A. Molecular basis of beta-thalassemia in the population of Tunisia. Hemoglobin 2004;28:177-87.
  6. Phylipsen M, Amato A, Cappabianca MP, et al. Two new betathalassemia deletions compromising prenatal diagnosis in an Italian and a Turkish couple seeking prevention. Haematologica 2009;94:1289-92.
  7. Moumni I, Zorai A, Daoued BB, et al. Hb A2-Pasteur-Tunis [delta59(E3)Lys-->Asn, AAG-->AAC]: a new delta chain variant detected by DNA sequencing in a Tunisian carrier of the codon 39 (C-->T) beta0-Thalassemia mutation. Hemoglobin 2007;31:23-9.
  8. Huisman THJ, Carver MFH, Baysal E. A Syllabus of Thalassemia Mutations (1997). Augusta: The Sickle Cell Anemia Foundation. 1997 (http://globin.cse.psu.edu).
  9. Frischknecht H, Dutly F. Two new delta-globin mutations: Hb A2-Ninive [delta133 (H11)Val-Ala] and a delta(+)-thalassemia mutation [-31 (A --> G)] in the TATA box of the delta-globin gene. Hemoglobin 2005;29:151-4.
  10. De Angioletti M, Di Girgenti C, Messineo R, Capra M, Carestia C. Hb A2-Monreale [delta146(HC3)His-->Arg], a novel delta chain variant detected in west Sicily. Hemoglobin 2002;26:1-5.
  11. Walker L, Patterson M, Eng B, McFarlane A, Waye JS. Identification of a new delta chain hemoglobin variant in a betathalassemia carrier: Hb A2-mumc [delta13(a10)Ala-->Asp]. Hemoglobin 2005;29:285-7.
  12. Pavlou E, Phylactides M, Kyrri A, et al. Delta-thalassemia in Cyprus. Hemoglobin 2006;30:455-62.
  13. Bouva MJ, Harteveld CL, van Delft P, Giordano PC. Known and new delta globin gene mutations and their diagnostic significance. Haematologica 2006;91:129-32.