Thalassemia in Iran; an Overview
F. Habibzadeh,* M. Yadollahie,* A. Merat,** M. Haghshenas***
*NIOC Outpatient Polyclinics, **Department of Biochemistry, ***Division of Hematology/Oncology and Bone Marrow Transplantation, Department of Internal Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
Embracing her four-year-old child, she entered the emergency room in a hurry. "Help, somebody help ...", the young lady cried with a trembling voice. "I've never let his hemoglobin drop below 10, and this is why his face is still normal", she added in a deep-seated sorrow. The needling marks over the limbs of the boy, were witness to so many fruitless endeavors for finding a proper site for blood transfusion. Then, his prostrated mother, with a glance of hope in her tearful eyes, asked our experienced nurses to get done the unfinished job. While all nurses were crying, one approached the child with a needle to try her chance. "What have I done that I am being punished for?", the poor little child asked. No one had any answer. Alas, the kid had thalassemia.
From the Memorandum of a Physician
Keywords · Hemoglobinopathies · thalassemia · demography · geography
Introduction
It is very hard to realize that your child has an incurable disease. It is even harder to cope with the feeling that you, yourself, are responsible for his/her suffering and pain. Thalassemia is a dreadful inherited disease affecting tens of thousands of people and is the most prevalent single-gene autosomal hereditary disease worldwide. The disease is very rare in the United States surprisingly enough, however, it was Thomas B. Cooley, a pediatrician from Detroit, who first recognized the condition in 1925.1 He noted a number of infants who became seriously anemic and developed splenomegaly during their first years of life. Very soon, the disease, was named after him, Cooley's anemia. Subsequently, in 1936, George Whipple and Lesley Bradford, both also from the United States, uncovered that all disorders designated diversely as von Jaksch's anemia, splenic anemia, Cooley's anemia, erythroblastosis, and Mediterranean anemia, were in fact a single entity, mostly seen in patients who came from the Mediterranean area, hence to name the disease they proposed 'thalassemia' derived from the Greek word 'q a l a s s a ', meaning 'the sea'.
Thalassemia in the World
Thalassemias are the commonest monogenic diseases worldwide. They are, however, heterogenous at the molecular level. More than 23 different molecular defects have been identified for a -thalassemia to date. The case in ß-thalassemia, with over 150 various known mutations, is even more perplexing.2 Each population-at-risk, however, has its own spectrum of common mutations, usually from five to ten; a finding that simplifies mutation analysis, and thus, determine the origin of the mutant genes.
Thalassemia is found in some 60 countries with the highest prevalence in the Mediterranean region, parts of North and West Africa, the Middle East, the Indian subcontinent, southern Far East and southeastern Asia, together composing the so-called thalassemia belt. In western countries, thalassemia affects mostly individuals whose ancestry are traceable to a high prevalence areas.3-6 As an example, there are around 1,000 cases of ß-thalassemia major in the United States, most of whom are descendants of Mediterranean, Asian Indian, South Asian, or Chinese ancestors.3 This figure is even less than half of the number of ß-thalassemic patients in Fars Province, a region only 120,000 km2 large in southern Iran.7
The distribution of the disease, even in the thalassemia belt is not uniform. The highest frequency of the a -thalassemia genes is found in Southeast Asia and among those whose ancestors settled there from the West Coast of Africa. The population of northern Thailand, with a prevalence of about 5% to 10%, harbors one of the highest incidences of a -thalassemia in the world.8 The incidence of a -thalassemia carriers in Portugal is also high (10%).9 In the eastern oases of Saudi Arabia, more than half of the people have a clinically silent form of a -thalassemia.10 With the resettlement of nearly two million refugees from Cambodia, Laos, and Vietnam in the 1970s and 80s, in the United States and Europe, symptomatic a -thalassemia syndromes, although still insignificant, appear to gain more importance.11
About 150 million people worldwide carry ß-thalassemia genes. The genes are particularly prevalent in Italy and Greece. Other regions with the high gene frequency are Sardinia (11-34%),12 Sicily (10%),13 Greece (5-15%),13 and Iran (4-10%)7. High prevalence of both a - and ß-thalassemia is also present in southern China and Taiwan.14
Such a defined geographic distribution is perhaps due to the inherent resistance against malaria in populations that carry the defective gene. In the South West Pacific region, the striking geographic correlation between the frequency of a -thalassemia and the endemicity of Plasmodium falciparum suggests that the former hemoglobinopathy provides a selective advantage against malaria.15 On the northern coast of Papua New Guinea, where malaria transmission is intense and a -thalassemia affects more than 90% of population, the risk of having severe malaria is 0.4 in a -thalassemia homozygotes and 0.7 in heterozygotes when compared with normal children.15 In a study of childhood malaria on the southwestern Pacific island of Espiritu Santo in Vanuatu, nonetheless, it was found that, paradoxically, both the incidence of uncomplicated malaria and the prevalence of splenomegaly, an index of malaria infection, were significantly higher in young a -thalassemic children compared to normal children.16 The a -thalassemias may have been selected for their ability to beneficially increase susceptibility to P. vivax, which induces limited cross-species protection against subsequent severe P. falciparum malaria by acting as a natural vaccine in these communities. Wonderfully, this malaria-resistance gene, through an unknown mechanism, also protects the affected person against diseases caused by infections other than malaria.15
A major factor for genetic diversity and thalassemia gene dissemination is the migration of people. The disease is highly prevalent in Southeast Asians of California, with an incidence of one in every 2,600 births. Carrier states are also found in virtually every ethnic group residing in the region, with higher-than-expected rates in non-Hispanic whites (1:600 births).3 The majority of ß-thalassemia carriers in India have been migrants from Pakistan.17 Many of ß-thalassemia gene mutations detected in Lebanon, were of Turkish, Iranian, Kurdish, Bulgarian and Asian Indian origin.18 In Turkish Kurdistan, the primary mechanism for the development of ß-thalassemia is genetic admixture with the local population.19 In a study carried out in Argentina, it was revealed that the diversity of ß-thalassemic alleles, together with their distribution, were similar to that found in the Mediterranean area.20 In another more recent investigation, it has been found that ß-thalassemia in Argentina originated mainly from Italian immigrants.21 And, in Germany, ß-thalassemia has originated from the Mediterranean region in about two-thirds of cases.5
Thalassemia in Iran
Iran, a country 1,648,000 km2 wide, has, like many other countries in the region, a large number of major thalassemia patients.7 a -thalassemia is very rare in Iran. The gene frequency of ß-thalassemia, however, is high and varies considerably from area to area, having its highest rate of more than 10% around the Caspian sea, and Persian Gulf. The prevalence of the disease in other areas is between 4% and 8%. In Isfahan, a city built around the river Zayandeh-Rood in the central part of Iran, the frequency rises again to about 8%. In the Fars Province, in southern Iran, the gene frequency is also high and reaches 8-10%.7
Among some ethnic groups, for unknown reasons, the gene frequency has remained high. Iranian Jews represent an ancient community with a high degree of inbreeding. Although the community has remained relatively isolated, it has had strong ties with Babylonian Jewry in Iraq.22 As a consequence, ß-thalassemia is prevalent among both the Iranian and the Iraqi Jewish communities. This is similar to what has happened to the Palestinian Arabs in whom, as a consequence of the high consanguinity rate, many recessive traits, such as ß-thalassemia, are present with a relatively high frequency.23
Heretofore, a few studies on the clinical and laboratory presentations of homozygous ß-thalassemia have been conducted in Iran, and unfortunately, no systematic large-scale study has been performed to elucidate the status of thalassemia in Iran.24-26 In a recent study on 17 ß-thalassemia patients, in spite of the small sample size, it has been clearly shown that mutations in this region, are very diverse.27 Moreover, it was learned that in southern Iran, the IVS-II-1 (G® A) mutation is the most frequent (31%) mutation for ß-thalassemia.27
There are numerous gene mutations responsible for ß-thalassemia in Iran.27 These mutations are of Iranian, Mediterranean, Kurdish, Turkish, Egyptian, Tunisian, Indian, Asian Indian, Chinese, and Afro-American origin.7 This marked heterogeneity may be, in part, due to the Islamic educations, which emphasizes fraternity and hospitality, and urges Muslims to accept newcomers with open arms. It parallels the situation in Lebanon where, from the genetic point of view, the Sunni Muslims that constitute the most heterogeneous religious group, have 13 mutations for ß-thalassemia, while only two mutations have been found among the Christian Maronites.18
Iran, a country in the center of the Middle East and on the route of the ancient Silk Road, has been the meeting place of the Eastern and Western civilizations. During its long history, Iran has been occupied many times by invaders, many of whom became residents of the region. According to a recent UN-report, Iran is hosting the world's largest number of refugees, mostly from Iraq and Afghanistan, during the past two decades. This bulky ethnic/genetic admixture has resulted in an unexpectedly high number of different mutations that account for ß-thalassemia in this genetic melting pot. The presence of so many dissimilar mutations in the globin gene clusters of the Iranian population, can certainly be considered as an evidence of its past colonizations.
Treatment
Not long ago, children born with thalassemia seldom survived their first decade of life. Nowadays, the age of patients with ß-thalassemia major is increasing because of better treatment and supportive measures.28 Homozygosity or compound heterozygosity for ß-thalassemia usually results in transfusion-dependent thalassemia major and, rarely, in mild non-transfusion-dependent thalassemia intermedia conditions.2 Thalassemia intermedia is a clinical diagnosis characterized by a symptomatic but less severe condition relative to the ß-thalassemia major. Thalassemia intermedia may arise from several different combinations of a - and/or ß-thalassemia mutations.29 These populations because of extramedullary hematopoiesis, although needing no blood transfusion, require special long persisting medical attentions.
Blood Transfusion:
To stay alive, patients with thalassemia major must receive at least 150-350 mL of packed red cells every two to four weeks. It is a life-long process that usually begins sometime in the first year of life. According to the Iranian National Blood Transfusion Center, the country harbors about 20,000 thalassemia major patients. This amounts to 250 tons of blood each year just to treat thalassemic patients. For thalassemic patients alone, about 350,000 blood bags are needed annually, costing about US $3 a piece. This translates into US $1,000,000 annually.
In the western countries most people are willing to donate blood. In many third world countries, unfortunately, the situation is different. In Iran, now and then, employees of government organizations donate blood in groups, a movement that can be called an "obligatory volunteer" system, which supplies much of the needed blood. Because of the widespread poverty in most parts of the developing countries, people do not get enough nourishment in their food. Sometimes it is discovered that the donor's own hemoglobin level is too low. These reasons are why blood banks in the third world often remain short of blood.
Collection of blood is only the beginning of the story. Transfusions require clean blood, free from infectious diseases. Each blood sample should be tested for hepatitis B, AIDS, and syphilis. Fortunately, AIDS is almost non-existent in this country, although a few carriers have been identified among our donors. Homosexuality and prostitution are prohibited and addicts are more likely to smoke (opium) than to inject illicit drugs. All these, help to minimize the risks of hepatitis and AIDS.
Many studies have indicated high prevalences of hepatitis C, E, and G viruses in multiply-transfused patients. In one study, 24 of 101 (23.8%) thalassemic patients, tested positive for the antibody to hepatitis C virus (HCV).30 In other studies performed on ß-thalassemic patients of the Fars province, southern Iran, very high prevalences (27% to 68%) of anti-HCV in multiply-transfused patients has been reported.31,32 In one report, the prevalence of anti-HCV and hepatitis G virus (HGV) RNA were 17%, and 14%, respectively, in 42 multiply-transfused children.33 The same study revealed that although the frequency of anti-HCV dropped sharply after implementation of HCV screening, the prevalence of HGV viremia remained unchanged. The prevalence of anti-HCV has been found to be 57.1% in ß-thalassemia patients in Saudi Arabia. This value is significantly higher than 2.8% seen among the Saudi normal population.34 Meanwhile, anti-hepatitis E virus (HEV) has been detected in 10.7% of the Saudi ß-thalassemic patients. It has been concluded that although the difference in HEV seropositivity between ß-thalassemia major and the control was not statistically significant, the possibility of blood-borne HEV could not be excluded.34 All these findings, indicate the importance of routine screening of donated blood for infectious diseases, particularly for HCV.35
Another side of the coin is that, blood transfusion, although life saving, loads body with excess iron that eventually may result in hemosiderosis and its associated complications. Multiple endocrinopathies, including hypogonadism, hypoparathyroidism and diabetes mellitus, occur mainly in older patients who tend to have high serum ferritin levels. Prognosis for survival is greatly improved if the serum ferritin level is kept below 2,000 m g/L by regular chelation.36 Long-term studies of desferrioxamine [Desferal®] (DFO) therapy in multiply-transfused patients with ß-thalassemia major have clearly shown that it is generally safe and effective. Patients who begin with the treatment at young age can be protected from the lethal complications of iron overload for at least two decades, but chelation therapy may not always prevent or ameliorate late growth failure and/or delayed or absent puberty.37 Patients with iron-induced cardiomyopathy and possibly injuries to other organs may experience stability or improvement in function with intense chelation. High-dose intravenous DFO produces a rapid decrease in hepatic iron content and improved cardiac function but can also cause severe toxicity, as can normal doses in patients with a low iron burden.37 To achieve a satisfactory result, DFO has to be administered via painful subcutaneous infusions, for 8-10 hours each day, five to seven days a week, for life. DFO, however, is an expensive drug, and to provide the adequate amount for Iranian thalassemics, US $40,000,000 should be spent annually.
Nowadays, research is underway to find a way to administer iron chelation orally instead of by needle. Recently, a protein that is the single most critical known element in iron metabolism has been identified and characterized by scientists at the Harvard University.38 This protein may provide researchers the necessary information about ways to treat hemosiderosis, and iron overload.
Bone Marrow Transplantation:
The impressive improvement in the life expectancy of patients with ß-thalassemia major, observed over the past three decades is primarily due to the institution of effective transfusion regimens and adequate iron chelation therapy with nightly subcutaneous infusion of DFO. The first successful "cure" of ß-thalassemia was demonstrated in a young patient in 1981, when the first bone marrow transplantation (BMT) was done.39 Recent progress in transfusion techniques, pharmacology, molecular genetics, transplant immunology, and clinical skill today, surely heralds promise for further advancement of our knowledge in the treatment of the disease in future.
The only known treatment for thalassemia is BMT. But, finding a suitable bone marrow match is a very tedious enterprise. Seldom, can a sib or even a parent be found, but that is about all. Even after selection of a perfect donor, the procedure is very expensive and still quite risky. The patient has a 5-20% risk of dying from associated complications and runs another 5-15% chance that the transplant will not become functional. The condition is even worse for patients in advanced stages of the disease. Using a multivariate analysis, Guido Lucarelli of Pesaro, Italy, who is considered the most experienced thalassemia-related BMT expert, has indicated that portal fibrosis and either the presence of hepatomegaly or a history of insufficient DFO therapy are markedly associated with decreased chances of long-term and event-free survival.40 In addition, he suggests that on account of the high likelihood of cure with little early or late mortality and morbidity in class 1 Pesaro classification disease (i.e., no portal fibrosis, no hepatomegaly, and history of adequate chelation therapy), BMT be performed with no delay in patients who have already HLA-matched donors.41 Previously, about one third of the Iranian ß-thalassemic patients were first diagnosed when they were over four years of age.24 Almost all of our patients who have sofar undergone BMT belonged to class 3 disease, and hence, the majority had a poor outcome. Unfortunately, such end-stage patients are not uncommon in developing countries, where for lack of adequate blood transfusion and unsatisfactory DFO therapy, the disease has frequently progressed to advanced stages within a few years. Moreover, the necessary equipment and measures for BMT, are still not available in most of the countries where thalassemias are prevalent.
Promising Results in Gene Therapy:
During the past two decades, developments in molecular and cellular biology have kindled the hope that one might ultimately alleviate or even cure some grave genetic diseases by repairing or replacing the defected involved gene. Recently, researchers at the Columbia University have succeeded, for the first time, in demonstrating a high level and long-term expression of a transferred normal human ß-globin gene in an animal model.42 After gene transfer, the presence of the human ß-globin gene could be detected up to eight months later with high levels of expression. In this animal experiment, 20% of the total ß-globin produced in one mouse, was from the human gene. Another practical approach seems to be the re-activation of the fetal globin genes. This can correct the deranged pathophysiology of the hemoglobinopathies, because the presence of g -chains can neutralize the toxic effects of the unbound a -globin chains in the ß-thalassemias.43
Scientists are studying the dilemma and are trying to develop better gene transfer systems and hope to find safe ways to introduce normal genes into human hematopoietic stem cells. Until that day arrives, the only realistic way to cope with the socio-economic burden of the disease is to prevent the birth of victims with homozygous thalassemia.
The fertility rate in Southeast Asian families is relatively high, with an average of more than five children for each married woman.44 Birth control of ß-thalassemia by carrier screening, genetic counselling and prenatal diagnosis has been successful in many countries. In Sardinia, the program has been effective, as indicated by the reduction of the birth rate of thalassemia major from 1:250 to 1:4,000 live births.45 In Isfahan, in central Iran, the program has had also successful results.46 However, attitudes about health care, reasons why one seeks medical attention, and a variety of other cultural issues may hamper the effectiveness of genetic counseling and other preventive measures designed to reduce the incidence of thalassemia.44 Due to religious restrictions on abortion, termination of pregnancy after perinatal diagnosis is almost impossible in some Islamic countries. As a result, establishment of carrier screening programs and use of genetic counselling centers remain the only relevant ways that can help reduce the birth rate of new thalassemia cases in these countries.
Good screening, however, requires reliable diagnostic tools. In Iran, performing hemoglobin electrophoresis for detection of thalassemia carriers is now imperative for all couples before marriage. The test, however, is somewhat expensive, and it is gradually being replaced by the newly-advented molecular diagnostic kits. The main requirements for methodologies providing molecular diagnosis are speed, cost, convenience and the ability to test for multiple mutations simultaneously. For ß-thalassemia mutations the procedures that meet these requisites are the amplification refractory mutation system (ARMS) and the reverse dot-blot hybridization system.47 Nevertheless, on account of the existence of many mutations in Iran, the use of several primers for an accurate diagnosis is necessary.
Survival alone is not the solution for the victims of thalassemia. We have to find ways to provide quality of life for these patients and to support their families who become easily devastated morally and financially. Our task is to provide hope and compassion to these children and their parents until a cure is found. A better understanding of the demographics of thalassemia has the potential to aid in the more efficient utilization of health care resources and improved planning and provision of health care services. Therefore, depending on where we are living, we have to find a balance between trying to solve day to day problems while making long range plans.
Acknowledgement
The authors thank Dr. Mark Gettner for his valuable suggestions.
References
1 Cooley TB, Lee P. Series of cases of splenomegaly in children with anemia and peculiar bone change. Trans Am Pediatr Soc 1925; 37:29.
2 Cao A, Saba L, Galanello R, Rosatelli MC. Molecular diagnosis and carrier screening for beta thalassemia. JAMA 1997 Oct 15; 278(15):1273-7.
3 Lorey FW, Arnopp J, Cunningham GC. Distribution of hemoglobinopathy variants by ethnicity in a multiethnic state. Genet Epidemiol 1996; 13(5):501-12.
4 Birgens HS, Karle H, Guldberg P, Guttler F. [Hemoglobinopathy in the county of Copenhagen]. Ugeskr Laeger 1997 Jun 16; 159(25):3934-9. [Article in Danish]
5 Vetter B, Schwarz C, Kohne E, Kulozik AE. Beta-thalassaemia in the immigrant and non-immigrant German populations. Br J Haematol 1997 May; 97(2):266-72.
6 Rengelink-van der Lee JH, Schulpen TW, Beemer FA. [Incidence and prevalence of hemoglobinopathies in children in The Netherlands]. Ned Tijdschr Geneeskd 1995 Jul 22; 139(29):1498-501. [Article in Dutch]
7 Haghshenas M, Zamani J. [Thalassemia]. 1st ed. Shiraz: Shiraz University of Medical Sciences Publishing Center, 1997. [Book in Persian]
8 Lemmens-Zygulska M, Eigel A, Helbig B, et al. Prevalence of alpha-thalassemias in northern Thailand. Hum Genet 1996 Sep; 98(3):345-7.
9 Peres MJ, Carreiro MH, Machado MC, et al. [Neonatal screening of hemoglobinopathies in a population residing in Portugal]. Acta Med Port 1996 Apr; 9(4-6):135-9. [Article in Portuguese]
10 Pembrey ME, et al. Haemoglobin Bart's in Saudi Arabia. Br J Haematol 1975 Feb; 29(2):221-34.
11 Anderson HM, Ranney HM. Southeast Asian immigrants: The new thalassemias in Americans. Semin Hematol 1990 Jul; 27(3):239-46.
12 Guiso L, Frogheri L, Pistidda P, et al. Frequency of delta+ 27-thalassaemia in Sardinians. Clin Lab Haematol 1996 Dec; 18(4):241-4.
13 Lukens JN. The thalassemias and related disorders, quantitative disorders of hemoglobin synthesis. In: Lee GR, Bithell TC, Foerster J, et al, eds. Wintrobe's Clinical Hematology. 9th ed. Philadelphia: Lea & Febiger, 1993: 1102-45.
14 Ko TM, Xu X. Molecular study and prenatal diagnosis of alpha- and beta-thalassemias in Chinese. J Formos Med Assoc 1998 Jan; 97(1):5-15.
15 Allen SJ, O'Donnell A, Alexander ND, et al. a +-Thalassemia protects children against disease caused by other infections as well as malaria. Proc Natl Acad Sci U S A 1997 Dec 23; 94(26):14736-41.
16 Romana M, Keclard L, Guillemin G, et al. Molecular characterization of beta-thalassemia mutations in Guadeloupe. Am J Hematol 1996 Dec; 53(4):228-33.
17 Verma IC, Saxena R, Thomas E, Jain PK. Regional distribution of beta-thalassemia mutations in India. Hum Genet 1997 Jul; 100(1):109-13.
18 Zahed L, Talhouk R, Saleh M, et al. The spectrum of beta-thalassaemia mutations in the Lebanon. Hum Hered 1997 Sep; 47(5):241-9.
19 Rund D, Cohen T, Filon D, et al. Evolution of a genetic disease in an ethnic isolate: beta-thalassemia in the Jews of Kurdistan. Proc Natl Acad Sci U S A 1991 Jan 1; 88(1):310-4.
20 Varela V, Abreu S, Rossetti LC, Targovnik H. [Most frequent beta-thalassemia mutations in the Argentinean population]. Sangre (Barc) 1996 Apr; 41(2):137-40. [Article in Spanish]
21 Roldan A, Gutierrez M, Cygler A, et al. Molecular characterization of beta-thalassemia genes in an Argentine population. Am J Hematol 1997 Mar; 54(3):179-82.
22 Zlotogora J. Hereditary disorders among Iranian Jews. Am J Med Genet 1995 Jul 31; 58(1):32-7.
23 Zlotogora J. Autosomal recessive diseases among Palestinian Arabs. J Med Genet 1997 Sep; 34(9):765-6.
24 Nasab AH. Clinical and laboratory findings in the initial diagnosis of homozygous beta thalassaemia in Fars Province, Iran. Br J Haematol 1979 Sep; 43(1):57-61.
25 Daneshbod G. A biochemical study in anemic children in Iran. Acta Med Iran 1974 Dec; 17(3-4):141-7.
26 Gharib R, Ayazi S. Electrocardiographic findings in Iranian children with severe chronic anemia. Observations in iron deficiency, thalassemia major, and miscellaneous other anemic states. Clin Pediatr (Phila) 1972 Nov; 11(11):630-3.
27 Merat A, Haghshenas M, Pour ZM, et al. Beta-thalassemia in southwestern Iran. Hemoglobin 1993 Oct; 17(5):427-37.
28 Pearson HA, Cohen AR, Giardina PJ, Kazazian HH. The changing profile of homozygous beta-thalassemia: demography, ethnicity, and age distribution of current North American patients and changes in two decades. Pediatrics 1996 Mar; 97(3):352-6.
29 Ballas SK, Cai SP, Gabuzda T, Chehab FF. Molecular basis of asymptomatic beta-thalassemia major in an African American individual. Am J Med Genet 1997 Mar 17; 69(2):196-9.
30 Laosombat V, Pornpatkul M, Wongchanchailert M, et al. The prevalence of hepatitis C virus antibodies in thalassemic patients in the south of Thailand. Southeast Asian J Trop Med Public Health 1997 Mar; 28(1):149-53.
31 Saberi-Firoozi M, Yazdankhah S, Karbasi HT. Anti-HCV seropositivity among multiply transfused patients with ß-thalassemia major in southern Iran. Irn J Med Sci 1996; 21(1&2):56-9.
32 Ghaderi AA, Habib-Agahi M. High prevalence of anti-HCV and HTLV-1 antibodies in thalassemia-major patients of southern Iran. Irn J Med Sci 1996; 21(1&2):60-2.
33 Chung JL, Kao JH, Kong MS, et al. Hepatitis C and G virus infections in polytransfused children. Eur J Pediatr 1997 Jul; 156(7):546-9.
34 al-Fawaz I, al-Rasheed S, al-Mugeiren M, et al. Hepatitis E virus infection in patients from Saudi Arabia with sickle cell anaemia and beta-thalassemia major: possible transmission by blood transfusion. J Viral Hepat 1996 Jul; 3(4):203-5.
35 Habibzadeh F, Haghshenas M. Hepatitis C. Irn J Med Sci 1996; 21(1&2):1-2.
36 Low LC. Growth, puberty and endocrine function in beta-thalassaemia major. J Pediatr Endocrinol Metab 1997 Mar; 10(2):175-84.
37 Giardina PJ, Grady RW. Chelation therapy in beta-thalassemia: the benefits and limitations of desferrioxamine. Semin Hematol 1995 Oct; 32(4):304-12.
38 Fleming MD, Romano MA, Su MA, et al. Nramp2 is mutated in the anemic Belgrade (b) rat: evidence of a role for Nramp2 in endosomal iron transport. Proc Natl Acad Sci U S A 1998 Feb 3; 95(3):1148-53.
39 Thomas ED, Buckner CD, Sanders JE, et al. Marrow transplantation for thalassemia. Lancet 1982; 2:227-9.
40 Lucarelli G, Galimberti M, Polchi P, et al. Bone marrow transplantation in patients with thalassemia. N Engl J Med 1990 Feb 15; 322(7):417-21.
41 Lucarelli G, Galimberti M, Polchi P, et al. Marrow transplantation in patients with thalassemia responsive to iron chelation therapy. N Engl J Med 1993 Sep 16; 329(12):840-4.
42 Raftopoulos H, Ward M, Leboulch P, Bank A. Long-term transfer and expression of the human beta-globin gene in a mouse transplant model. Blood 1997 Nov 1; 90(9):3414-22.
43 Loukopoulos D. New therapies for the haemoglobinopathies. J Intern Med Suppl 1997; 740:43-8.
44 Glader BE, Look KA. Hematologic disorders in children from southeast Asia. Pediatr Clin North Am 1996 Jun; 43(3):665-81.
45 Cao A, Rosatelli MC, Galanello R. Control of beta-thalassaemia by carrier screening, genetic counselling and prenatal diagnosis: the Sardinian experience. Ciba Found Symp 1996; 197:137-51.
46 Ghanei M, Adibi P, Movahedi M, et al. Pre-marriage prevention of thalassaemia: report of a 100,000 case experience in Isfahan. Public Health 1997 May; 111(3):153-6.
47 Old J. Haemoglobinopathies. Prenat Diagn 1996 Dec; 16(13):1181-6.