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Thalassemia intermedia due to homozygosity for an Asian Indian (Aγδβ)° deletional inversion
Clinica Chimica Acta 385 (2007) 81 – 83 www.elsevier.com/locate/clinchim
Letter to the Editor Thalassemia intermedia due to homozygosity for an Asian Indian (Aγδβ)° deletional inversion
Dear Editor, δβ thalassemia and HPFH are heterogeneous disorders characterized by elevated levels of fetal hemoglobin. Heterozygotes of (δβ)° thalassemia have elevated γ chain production (Hb F − 5% to 20%) with reduced red cell indices [1]. Homozygous (δβ)° thalassemia patients usually present clinically as mild thalassemia intermedia [2]. Majority of individuals with HPFH or δβ thalassemia synthesize both Gγ and Aγ chains as in normal individuals. However, often only Gγ chains are elevated. These cases are referred to as Gγ δβ thalassemia [3] or Gγ HPFH [4], although they often show a rather similar hematological and clinical picture. δβ thalassemia is usually caused by large deletions of a variable extent in the β globin gene cluster. Ten deletions, which remove part of δ and β globin genes, have been described [5]. We report here the molecular characterization of a homozygous Gγ (Aγδβ)° thalassemia patient who presented clinically like a thalassemia intermedia. Hematological parameters were measured on an automated cell counter (Sysmex K 1000). HbA2 and Hb F levels were measured using the Variant Hemoglobin Testing System (BioRad Labs., Hercules, CA). Iron studies were done by standard methods [6]. A gap PCR-based strategy was used to screen for mutations [7]. The propositus was a 32-y male, born of a non-consanguineous marriage. He was referred to the hospital with a history of jaundice and a lump on the left side of the abdomen. He had no history of blood transfusions. His physical examination revealed normal height, weight and development for his age, with no skeletal abnormalities. His vitals were normal. He was pale having deep jaundice but no signs of hepatocellular failure. He had an enlarged liver of 8cm and a spleen of 12cm. CT scan of the abdomen showed hemochromatosis of liver with cholelithiasis. His liver biopsy showed increased iron in the parenchymal cells. His iron studies showed serum iron 243μg/ dl, ferritin 2406ug/μl, TIBC 249μg/dl, %saturation 98%. He is now on oral iron chelation for secondary hemochromatosis and is doing well. Fig. 1 shows the hematological data of the propositus and his family members. Hemoglobin analysis of the propositus was suggestive of homozygous β° thalassemia (Hb F 99.0%, HbA2 − 0.2%). Peripheral blood smear revealed only mild morphological changes. Hematological analysis of family members showed the presence of a raised Hb F determinant. His 0009-8981/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.cca.2007.07.011
parents showed nearly normal RBC indices with raised Hb F levels along with a pancellular distribution of HbF in F cells. These characteristics are suggestive of HPFH. The main reason for suspecting δβ thalassemia in the propositus was his thalassemia intermedia like clinical presentation. Using a gap PCR-based strategy, we first looked for the 3 known Hb F determinants in the Indian population (HPFH − 3, Indian GγAγ (δβ)° thalassemia, Asian Indian inversion Gγ (Aγδβ)° thalassemia. We found that the propositus was homozygous for the Asian Indian Gγ (Aγδβ)° thalassemia inversion (Fig. 2). This mutation is caused by a major rearrangement including an inversion of the sequence. Family studies done later on showed that both his parents and both children were heterozygous for this mutation. HPFH and δβ thalassemia are rare clinical disorders in India [8]. Here we are reporting an untransfused homozygous δβ thalassemia patient with iron overload presenting clinically like a thalassemia intermedia. Iron overload is infrequent in untransfused thalassemic patients. Nevertheless increased iron absorption by the gastrointestinal tract plays an important role in iron accumulation even in such untransfused cases. In these patients, iron storage increases with age [9] hence early diagnosis is important to prevent further complications. Sukumaran et al. 1972 [4] first described a case, homozygous for the Gγ type of fetal hemoglobin in India. They categorized this case as a Gγ HPFH homozygote because heterozygous relatives of this case had shown a pancellular distribution of Hb F and balanced α to non-α chain synthesis. Later on, Nakatsuji et al. [10] carried out restriction endonuclease analysis of the same patient and showed it to be a Gγ (Aγδβ)° thalassemia. Similarly, Amin et al. [11] described 2 patients with a thalassemia intermedia phenotype producing only Gγ chains. Chakrabarti et al. [12] have also reported presence of Gγ (Aγδβ)° thalassemia in the North Indian population. The thalassemia intermedia like clinical presentation of our propositus lead us to suspect that he might be a homozygote for (δβ)° thalassemia rather than homozygote for HPFH, the latter condition being asymptomatic. The clinical presentation of this case adds to the heterogeneity of phenotypes seen in these rare disorders of homozygous δβ thalassemia. Jones et al. [13] suggested that Gγ(Aγδβ)° deletional inversion cases and deletional cases of (Aγδβ)° thalassemia eliminate a region of the Alu repetitive sequence 5′ to the δ globin gene. This region is thought to play a regulatory role in γ gene expression and it is not entirely deleted in cases of (δβ)° thalassemia [14]. In such an event, the cases of (Aγδβ)° thalassemia may all be forms of HPFH and it would then be the total or partial deletion of the Aγ gene that causes the thalassemic clinical conditions. The varied
82
Letter to the Editor
Fig. 1. Hematological and molecular analysis in a Gγ(Aγδβ)° thalassemia family.
clinical presentations of these rare disorders of homozygous δβ thalassemia are important to document and add to the considerable heterogeneity of these disorders. References
Fig. 2. 1.5% agarose gel electrophoresis showing the presence of the Gγ(Aγδβ)° thalassemia Asian Indian deletional inversion in the family members.
[1] Rochette J, Craig JE, Thein SL. Fetal hemoglobin levels in adults. Blood Rev 1994;8:213–24. [2] Wood WG, Clegg JB, Weatherall DJ. Hereditary persistence of fetal hemoglobin (HPFH) and δβ thalassemia. Br J Hematol 1979;43: 509–20. [3] Orkin SH, Alter BP, Altay C. Deletion of the Aγ globin gene in Gγ δβ thalassemia. J Clin Invest 1979;64:866–9. [4] Sukumaran PK, Huisman THJ, Schroeder WA, et al. A homozygote for HbGγ type of fetal hemoglobin in India: a study of two Indian and four Negro families. Br J Hematol 1972;23:403–17. [5] Huisman THJ, Carver MFH, Baysal E. A syllabus of thalassemia mutations. The sickle cell anemia foundation, Augusta GA, USA; 1997. (http://globin.cse.psu.edu). [6] Dacie JV, Lewis SM. Practical hematology. 7th Ed. Edinburgh, London: Churchill Living stone; 1991. pp 412. [7] Craig JE, Barmetson RA, Prior J, Raven JL, Thein SL. Rapid detection of deletions causing δβ thalassemia and hereditary persistence of fetal hemoglobin by enzymatic amplification. Blood 1994;6:1673–82. [8] Agarwal MB. The burden of hemoglobinopathies in India — time to wake up? J Assoc Phys India 2005;53:1017–8.
Letter to the Editor [9] Gumruk F, Gurgey A, Duru F, Altay C. Re-evaluation of iron absorption and serum ferritin in β thalassemia intermedia. Pediat Hematol Oncol 1992;9:359–63. [10] Nakatsuji T, Gilman JG, Sukumaran PK, Huisman TH. Restriction endonuclease gene mapping studies of an Indian (Aγδβ)° thalassemia, previously identified as Gγ HPFH. Br J Hematol 1984;57:663–70. [11] Amin AB, Pandya NL, Diwin PP, et al. A comparison of the homozygous states for Gγ and GγAγδβ thalassemia. Br J Hematol 1979;43:537–48. [12] Chakrabarti P, Dash D, Panda BK. Detection of Gγ (Aγδβ)° thalassemia in North India. Clin Chim Acta 2006;364:363–4. [13] Jones RW, Old JM, Trent RJ, Clegg JB, Weatherall DJ. Restriction mapping of a new deletion responsible for Gγ (δβ)° thalassemia. Nucl Acid Res 1981;9:6813–25. [14] Ottolenghi S, Giglioni B, Taramelli R, et al. Molecular comparison of δβ thalassemia and hereditary persistence of fetal hemoglobin DNAs: evidence of a regulatory area? Proc Natl Acad Sci 1982;79:2347–51.
A. Nadkarni R. Surve ⁎ R. Colah K. Ghosh Institute of Immunohaematology (ICMR), 13th Floor, New Multistoried Building, K.E.M. Hospital Campus, Parel, Mumbai-4000 12, India ⁎ Corresponding author. Tel.: +91 22 24138518/19; fax: +91 22 24138521. E-mail address: [email protected] (R. Colah).
83
M. Holay A. Dani A. Shrikhande V. Bharti S. Suryawanshi Indira Gandhi Govt. Medical College, Nagpur, India 31 May 2007
Letter to the Editor Thalassemia intermedia due to homozygosity for an Asian Indian (Aγδβ)° deletional inversion
Dear Editor, δβ thalassemia and HPFH are heterogeneous disorders characterized by elevated levels of fetal hemoglobin. Heterozygotes of (δβ)° thalassemia have elevated γ chain production (Hb F − 5% to 20%) with reduced red cell indices [1]. Homozygous (δβ)° thalassemia patients usually present clinically as mild thalassemia intermedia [2]. Majority of individuals with HPFH or δβ thalassemia synthesize both Gγ and Aγ chains as in normal individuals. However, often only Gγ chains are elevated. These cases are referred to as Gγ δβ thalassemia [3] or Gγ HPFH [4], although they often show a rather similar hematological and clinical picture. δβ thalassemia is usually caused by large deletions of a variable extent in the β globin gene cluster. Ten deletions, which remove part of δ and β globin genes, have been described [5]. We report here the molecular characterization of a homozygous Gγ (Aγδβ)° thalassemia patient who presented clinically like a thalassemia intermedia. Hematological parameters were measured on an automated cell counter (Sysmex K 1000). HbA2 and Hb F levels were measured using the Variant Hemoglobin Testing System (BioRad Labs., Hercules, CA). Iron studies were done by standard methods [6]. A gap PCR-based strategy was used to screen for mutations [7]. The propositus was a 32-y male, born of a non-consanguineous marriage. He was referred to the hospital with a history of jaundice and a lump on the left side of the abdomen. He had no history of blood transfusions. His physical examination revealed normal height, weight and development for his age, with no skeletal abnormalities. His vitals were normal. He was pale having deep jaundice but no signs of hepatocellular failure. He had an enlarged liver of 8cm and a spleen of 12cm. CT scan of the abdomen showed hemochromatosis of liver with cholelithiasis. His liver biopsy showed increased iron in the parenchymal cells. His iron studies showed serum iron 243μg/ dl, ferritin 2406ug/μl, TIBC 249μg/dl, %saturation 98%. He is now on oral iron chelation for secondary hemochromatosis and is doing well. Fig. 1 shows the hematological data of the propositus and his family members. Hemoglobin analysis of the propositus was suggestive of homozygous β° thalassemia (Hb F 99.0%, HbA2 − 0.2%). Peripheral blood smear revealed only mild morphological changes. Hematological analysis of family members showed the presence of a raised Hb F determinant. His 0009-8981/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.cca.2007.07.011
parents showed nearly normal RBC indices with raised Hb F levels along with a pancellular distribution of HbF in F cells. These characteristics are suggestive of HPFH. The main reason for suspecting δβ thalassemia in the propositus was his thalassemia intermedia like clinical presentation. Using a gap PCR-based strategy, we first looked for the 3 known Hb F determinants in the Indian population (HPFH − 3, Indian GγAγ (δβ)° thalassemia, Asian Indian inversion Gγ (Aγδβ)° thalassemia. We found that the propositus was homozygous for the Asian Indian Gγ (Aγδβ)° thalassemia inversion (Fig. 2). This mutation is caused by a major rearrangement including an inversion of the sequence. Family studies done later on showed that both his parents and both children were heterozygous for this mutation. HPFH and δβ thalassemia are rare clinical disorders in India [8]. Here we are reporting an untransfused homozygous δβ thalassemia patient with iron overload presenting clinically like a thalassemia intermedia. Iron overload is infrequent in untransfused thalassemic patients. Nevertheless increased iron absorption by the gastrointestinal tract plays an important role in iron accumulation even in such untransfused cases. In these patients, iron storage increases with age [9] hence early diagnosis is important to prevent further complications. Sukumaran et al. 1972 [4] first described a case, homozygous for the Gγ type of fetal hemoglobin in India. They categorized this case as a Gγ HPFH homozygote because heterozygous relatives of this case had shown a pancellular distribution of Hb F and balanced α to non-α chain synthesis. Later on, Nakatsuji et al. [10] carried out restriction endonuclease analysis of the same patient and showed it to be a Gγ (Aγδβ)° thalassemia. Similarly, Amin et al. [11] described 2 patients with a thalassemia intermedia phenotype producing only Gγ chains. Chakrabarti et al. [12] have also reported presence of Gγ (Aγδβ)° thalassemia in the North Indian population. The thalassemia intermedia like clinical presentation of our propositus lead us to suspect that he might be a homozygote for (δβ)° thalassemia rather than homozygote for HPFH, the latter condition being asymptomatic. The clinical presentation of this case adds to the heterogeneity of phenotypes seen in these rare disorders of homozygous δβ thalassemia. Jones et al. [13] suggested that Gγ(Aγδβ)° deletional inversion cases and deletional cases of (Aγδβ)° thalassemia eliminate a region of the Alu repetitive sequence 5′ to the δ globin gene. This region is thought to play a regulatory role in γ gene expression and it is not entirely deleted in cases of (δβ)° thalassemia [14]. In such an event, the cases of (Aγδβ)° thalassemia may all be forms of HPFH and it would then be the total or partial deletion of the Aγ gene that causes the thalassemic clinical conditions. The varied
82
Letter to the Editor
Fig. 1. Hematological and molecular analysis in a Gγ(Aγδβ)° thalassemia family.
clinical presentations of these rare disorders of homozygous δβ thalassemia are important to document and add to the considerable heterogeneity of these disorders. References
Fig. 2. 1.5% agarose gel electrophoresis showing the presence of the Gγ(Aγδβ)° thalassemia Asian Indian deletional inversion in the family members.
[1] Rochette J, Craig JE, Thein SL. Fetal hemoglobin levels in adults. Blood Rev 1994;8:213–24. [2] Wood WG, Clegg JB, Weatherall DJ. Hereditary persistence of fetal hemoglobin (HPFH) and δβ thalassemia. Br J Hematol 1979;43: 509–20. [3] Orkin SH, Alter BP, Altay C. Deletion of the Aγ globin gene in Gγ δβ thalassemia. J Clin Invest 1979;64:866–9. [4] Sukumaran PK, Huisman THJ, Schroeder WA, et al. A homozygote for HbGγ type of fetal hemoglobin in India: a study of two Indian and four Negro families. Br J Hematol 1972;23:403–17. [5] Huisman THJ, Carver MFH, Baysal E. A syllabus of thalassemia mutations. The sickle cell anemia foundation, Augusta GA, USA; 1997. (http://globin.cse.psu.edu). [6] Dacie JV, Lewis SM. Practical hematology. 7th Ed. Edinburgh, London: Churchill Living stone; 1991. pp 412. [7] Craig JE, Barmetson RA, Prior J, Raven JL, Thein SL. Rapid detection of deletions causing δβ thalassemia and hereditary persistence of fetal hemoglobin by enzymatic amplification. Blood 1994;6:1673–82. [8] Agarwal MB. The burden of hemoglobinopathies in India — time to wake up? J Assoc Phys India 2005;53:1017–8.
Letter to the Editor [9] Gumruk F, Gurgey A, Duru F, Altay C. Re-evaluation of iron absorption and serum ferritin in β thalassemia intermedia. Pediat Hematol Oncol 1992;9:359–63. [10] Nakatsuji T, Gilman JG, Sukumaran PK, Huisman TH. Restriction endonuclease gene mapping studies of an Indian (Aγδβ)° thalassemia, previously identified as Gγ HPFH. Br J Hematol 1984;57:663–70. [11] Amin AB, Pandya NL, Diwin PP, et al. A comparison of the homozygous states for Gγ and GγAγδβ thalassemia. Br J Hematol 1979;43:537–48. [12] Chakrabarti P, Dash D, Panda BK. Detection of Gγ (Aγδβ)° thalassemia in North India. Clin Chim Acta 2006;364:363–4. [13] Jones RW, Old JM, Trent RJ, Clegg JB, Weatherall DJ. Restriction mapping of a new deletion responsible for Gγ (δβ)° thalassemia. Nucl Acid Res 1981;9:6813–25. [14] Ottolenghi S, Giglioni B, Taramelli R, et al. Molecular comparison of δβ thalassemia and hereditary persistence of fetal hemoglobin DNAs: evidence of a regulatory area? Proc Natl Acad Sci 1982;79:2347–51.
A. Nadkarni R. Surve ⁎ R. Colah K. Ghosh Institute of Immunohaematology (ICMR), 13th Floor, New Multistoried Building, K.E.M. Hospital Campus, Parel, Mumbai-4000 12, India ⁎ Corresponding author. Tel.: +91 22 24138518/19; fax: +91 22 24138521. E-mail address: [email protected] (R. Colah).
83
M. Holay A. Dani A. Shrikhande V. Bharti S. Suryawanshi Indira Gandhi Govt. Medical College, Nagpur, India 31 May 2007