Tóm tắt
Background: Alpha thalassaemia is a common monogenic disorder found in most parts of the world but the severe form is restricted in its distribution while the mild deletional form of α- thalassaemia has a wider geographical distribution.
Methods: One hundred and fifty one Nigerians which included 29 patients with unexplained recurrent haemolytic anaemia had their α-thalassaemia status determined by gap PCR after being screened using red cell indices.
Results: Only the -α 3.7 deletion occurs among Nigerians with a gene frequency of 0.21. Forty-two per cent of the study population are heterozygotes, 9% are homozygotes while 49% are normal for this deletion. The mean haematocrit for the study population is 37.5%: homozygote, heterozygotes and normal subjects had a mean haematocrit of 37.3%, 37.5% and 37.7% respectively. The mean mean corpuscular haemoglobin (MCH) and haematocrit are significantly lower for patients than controls (24±2.9pg Vs 26.6±2.5pg (p=.000), 29% Vs 40% (p=.000) respectively). Forty three percent of both patients and controls had MCH of less than 27pg but only 10% of patients had MCH that is greater than 27pg. Homozygote patients had a higher mean haematocrit than
patients who are normal for the deletion (34.7% Vs 25.4%, p=0.06) but homozygote patients had a lower mean haematocrit than homozygote controls (34.7% Vs 38.5%, p=0.4).
Conclusion: This would suggest that α-thalassaemia is not responsible for the recurrent haemolytic anaemia observed in these patients and that the high prevalence of microcytosis among the normal populace needs further exploration.
Keywords: α-thalassaemia, red cell indices, hypochromia, microcytosis, haemolytic anaemia
Abstract
Contexte: La thalassémie alpha est un trouble fréquent monogénique qu’on trouve presque partout dans le monde, mais la forme grave est limitée dans sa distribution, tout en la forme bénigne de la délétion á-thalassémie a une distribution géographique plus large.
Méthodes: Cent cinquante et un Nigérians y compris 29 patients atteints d’anémie hémolytique récurrente inexpliquée avaient leur statut d’á-thalassémie soit déterminé par espace PCR après projection à l’aide des indices de globules rouges.
Résultats: Seule la suppression du -á 3.7 se produit chez les Nigérians avec une fréquence de 0,21 gène. Quarante-deux pour cent de la population étudiée sont hétérozygotes, 9% sont homozygotes tandis que 49% sont normaux pour cette suppression. L’hématocrite moyen pour la population étudiée est de 37,5%: homozygote, hétérozygote et les sujets normaux avaient un hématocrite moyen de 37,3%, 37,5% et 37,7% respectivement. La moyenne corpusculaire, moyenne en hémoglobine (TCMH) et de l’hématocrite sont significativement plus faible pour les patients que chez les témoins (24 ± 26,6 ± 2.9pg Vs 2.5pg (p = .000), 29% vs 40% (p = 0,000), respectivement). Quarante-trois pour cent des patients et des contrôles des deux avait SMI de moins de 27pg mais seulement 10% des patients avaient le MCH qui est supérieure à 27pg. P Les patients homozygotes avaient un hématocrite plus élevé en moyenne que les patients qui sont normaux pour la suppression (34,7% vs 25,4%, p = 0,06), mais les patients homozygotes avaient un hématocrite inférieur en moyen que chez les témoins homozygotes (34,7% vs 38,5%, p = 0,4).
Conclusion: Ceci suggérait donc que l’á-thalassémie ne soit pas responsable de l’anémie hémolytique récurrente observée chez ces patients et que la prévalence élevée de microcytose parmi la population normale a besoin d’une exploration plus poussée.
Correspondence: Dr. T R. Kotila, Department of Haematology, College of Medicine, University of Ibadan, Ibadan, Nigeria. E-mail: tkotila@comui.edu.ng
Tài liệu tham khảo
Higgs DR, Vickers MA, Wilkie AO, Preteorius IM, Jarman AP and Weatherall DJ: A review of the molecular genetics of the human alpha-globin gene cluster. Blood 1989; 73: 1081-1104.
Embury SH. The different types of alpha-thalassaemia-2: Genetic aspects. Hemoglobin 1988; 12: 445-453.
Baysal E and Huisman TH. Detection of common deletional alpha-thalassaemia-2 determinants by PCR. Am J Hematol. 1994; 46: 208-213.
Hendrickse RG, Boyo AE, Fitzgerald PA and Kuti SR. Studies on the haemoglobin of newborn Nigerians. Br. Med. J 1960 1: 611-614.
Esan GJ. The thalassaemia syndromes in Nigeria. Br J Haematol. 1970; 19: 47-56.
Falusi AG, Esan GJ, Ayyub H and Higgs DR. Alpha Thalassaemia in Nigeria: its interaction with sickle cell disease. Eur J Haematol. 1987; 38: 370-375.
Oron-Karni V, Filon D, Oppenheim A and Rund D. Rapid detection of the common mediterranean alpha-Globin Deletions/Rearrangements Using PCR. Am J Hematol. 1998; 58: 306-310.
Bowden DK, Vickers MA and Higgs DR. A PCR –based strategy to detect the common severe determinants of alpha thalassaemia. Br J Haematol. 1992; 81: 104-108.
Dode C, Krishnamoorthy R, Lamb J and Rochette J. Rapid analysis of -alpha 3.7 thalassaemia and alpha alpha alpha anti3.7 triplication by enzymatic amplification analysis. Br. J Haematol 1993; 83: 105-111.
Bowie LJ, Reddy PL, Nagabhushan M and Sevigny P. Detection of alpha-thalassaemias by multiplex polymerase chain reaction. Clin Chem 1994; 40: 2260-2266.
Omotade OO, Kayode CM, Falade SL, Ikpeme S, Adeyemo AA and Akinkugbe FM. Routine screening for sickle cell haemoglobinopathy by electrophoresis in an infant welfare clinic. West Afr J Med.1998;17: 91-94.
Embury SH, Dozy AM, Miller J, Davis JR Jr, et al. Concurrent sickle cell anemia and alpha-thalassaemia: effect on severity of anaemia N Engl J Med 1982;306:270-274.
Steinberg MH, Rosenstock W, Coleman MB, Adams JG, et al. Effects of thalassaemia and microcytosis on the hematologic and vasoocclusive severity of sickle cell anemia. Blood 1984; 63:1353-1360.
Oluboyede OA and Williams AI. Serum ferritin and other iron indices in adult Nigerians with chronic renal failure -review of management of anaemia. Afr J Med Med Sci 1995;24:231-237.
Abudu OO, Macaulay K and Oluboyede OA. Serial evaluation of iron stores in pregnant Nigerians with hemoglobin SS or SC. J Natl Med Assoc. 1990; 82: 41-48.