Guideline:Thalassemia intermedia and Hb E

Definition
The clinical phenotypes of thalassaemia intermedia (TI) lie between those of thalassaemia minor (heterozygous state) and major (homozygous state), although there is substantial clinical overlap between the three conditions. TI was first described in 1955 by Rietti-Greppi-Micheli, who referred to patients as being ‘too haematologically severe to be called minor, but too mild to be called major’.

Thalassaemia intermedia encompasses a wide clinical spectrum. Mildly affected patients are completely asymptomatic until adult life, experiencing only mild anaemia and maintaining haemoglobin levels between 7- 10g/dL. These patients require only occasional blood transfusions, if any. Patients with more severe thalassaemia intermedia generally present between the ages of 2 and 6 years, and although they are able to survive without regular transfusion therapy, growth and development can be retarded. The clinical spectrum of thalassaemia intermedia indicates the need for an individualised treatment approach. Despite the availability of a number of treatment options, the lack of clear guidelines can present a significant clinical challenge (Taher, 2006; Camaschella and Cappellini, 1995).

Mechanism of TI
The pathophysiology of thalassaemias is based on an imbalance of globin-chain synthesis. In the case of‚ β-thalassaemia intermedia, the imbalance is greater than that seen in‚ β-thalassaemia trait and less than that of‚ β-thalassaemia major. Most TI patients are homozygotes or compound heterozygotes for‚ β-thalassaemia, meaning that both‚β-globin loci are affected. The mild clinical characteristics of TI compared with thalassaemia major are primarily the result of the following three mechanisms:
 * inheritance of a mild‚ β+mutation;
 * presence of a polymorphism for the enzyme Xmn-I in the Gγ- promoter region, associated with increased HbF; and
 * co-inheritance of α-thalassaemia on the‚ β-globin locus.

The phenotype of TI may also result from the increased production of α-globin chains, occurring either by the triplication of α-genotype associated with‚ β-heterozygosity, or by the interaction of‚ β- and δβ-thalassaemia (Taher, 2006).

Analysis of the genotypes of patients with thalassaemia intermedia is important for an early diagnosis of the milder disease, thus avoiding unnecessary blood transfusions.

Predicting phenotype from genotype in TI is still difficult, due to the interaction of genetic and environmental factors. Primary genetic modifiers are the numerous genetic alleles at the‚ β-chain locus, which can cause either complete or marked reduction in‚β- chain synthesis. Secondary genetic modifiers are those that have a direct effect on modifying the amount of excess α-chains (inheritance of abnormal α- or β-chain genes). Tertiary modifiers are polymorphisms occurring at loci involved in bone, iron and bilirubin metabolism that can affect clinical expression. Relevant environmental factors include social conditions, nutrition and the availability of medical care (Taher, Ismaeel and Cappellini, 2006).

Differential diagnosis
Differentiation at presentation between thalassaemia major and thalassaemia intermedia is essential for designing appropriate treatment for an individual patient. The accurate prediction of a mild phenotype may avoid needless transfusions and their complications, while the timely diagnosis of thalassaemia major will allow an early start to a transfusion programme, thus preventing or delaying hypersplenism and reducing the risk of red cell antigen sensitisation. Unfortunately, however, the accurate identification of these two phenotypes at the onset is remarkably difficult. Nevertheless, a careful analysis of clinical, haematological, genetic and molecular data may allow a reasonable conclusion for treatment (Taher, 2006; Wainscoat, 1987; Weatherall, 2001). (see Table 1, page 122 for an outline of the major differences between thalassaemia intermedia and major).

Pathophysiology of Thalassaemia Intermedia (TI)
Three main factors are responsible for the clinical sequelae of thalassaemia intermedia: ineffective erythropoiesis, chronic anaemia and iron overload. The severity of clinical sequelae depends primarily on the underlying molecular defects. a-chains are highly unstable and precipitate into erythroid precursors in the bone marrow, causing membrane damage and cell death (i.e. ineffective erythropoiesis). Hypertrophy of erythroid marrow in medullary and extramedullary sites, a consequence of severe ineffective erythropoiesis, results in characteristic deformities of the skull and face and may also cause cortical thinning and pathological fractures of long bones. The degree of ineffective erythropoiesis is the primary determinant of the development of anaemia, while peripheral haemolysis of mature red blood cells and an overall reduction in haemoglobin synthesis are secondary determinants.

Complications and management of TI
In addition to the defining symptoms of thalassaemia intermedia, which are seen to a lesser or greater extent in other forms of thalassaemia, patients with thalassaemia intermedia experience a number of specific complications that are rare in thalassaemia major. Figure 1 (page 123) highlights the multitude of complications in untreated thalassaemia (Taher, Ismaeel and Cappellini, 2006; Cappellini, Cerino et al, 2001).

Splenomegaly and Splenectomy
Splenectomy is now uncommon and is mainly performed late in life. The main indications for splenectomy in thalassaemia intermedia are a significant enlargement of the spleen and a decrease in mean haemoglobin levels in the absence of other transient factors such as infection (Taher, Ismaeel and Cappellini, 2006; Cappellini, Cerino et al, 2001; Borgna-Pignatti, Rigon, Merlo et al, 2003; Galanello, Piras, Barella et al, 2001). As for the type of surgery, the laparoscopic approach is safe and feasible and preferred over open surgery, as a minimally invasive alternative that may become the treatment of choice in ‚β-thalassaemia patients who require concurrent operations. During splenectomy, surgeons should assess the gallbladder for any stones and perform cholecystectomy whenever gallstones are found (Leandros et al, 2006).

Gall stones and cholecystectomy
Gallstones are much more common in thalassaemia intermedia than in thalassaemia major as a result of ineffective erythropoiesis and peripheral haemolysis. Similar to laparoscopic splenectomy, laparoscopic cholecystectomy has more favourable and feasible outcome than open cholecystectomy (Taher, Ismaeel and Cappellini, 2006; Cappellini, Cerino et al, 2001; Borgna- Pignatti, Rigon, Merlo et al, 2003; Galanello, Piras, Barella et al, 2001; Leandros et al, 2006).

Extramedullary haematopoiesis
Extramedullary haematopoiesis is a compensatory mechanism where bone marrow activity increases in an attempt to overcome the chronic anaemia of thalassaemia intermedia, leading to the formation of erythropoietic tissue masses that primarily affect the spleen, liver, lymph nodes, chest and spine. These masses can be detected by magnetic resonance imaging (MRI). They may cause neurological problems such as spinal cord compression and paraplegia, and intra-thoracic masses.

In case of spinal cord compression, clinical awareness is crucial for early diagnosis and prevention of irreversible neurological complications. MRI is the radiological method of choice for diagnosing extramedullary haematopoietic masses and for delineating the extent of spinal cord involvement.

Management includes transfusion therapy, as well as radiotherapy and hydroxyurea (Taher, Ismaeel and Cappellini, 2006; Chehal, Aoun, Koussa et al, 2003; Castelli, Graziadei, Karimi and Cappellini, 2004; Saxon, Rees, Olivieri, 1998). Hypertransfusion is a promising treatment method, targeting at higher Hb levels, involving many blood transfusions over a period of weeks to compensate for the demands of erythropoiesis.

Kidney stones
As a result of ineffective erythropoiesis and peripheral haemolysis TI patients are susceptible to kidney stones, which can lead to hydronephrosis and kidney failure. Thecause is associated with hypertrophic stones that block the renal tubules and even the calyces. The kidneys are frequently enlarged in thalassaemia, due to the presence of extramedullary haematopoiesis.

Leg ulcers
Leg ulcers are more common in older rather than younger patients with thalassaemia intermedia. It is unclear why ulcers develop. However, once an ulcer has started to develop it is very painful and difficult to cure, although regular blood transfusions may provide some relief in persistent cases. Zinc supplementation can help accelerate the healing of ulcers. Hydroxyurea also has some benefit, either alone or in combination with erythropoietin or platelet-derived growth factor. In addition, the use of an oxygen chamber can provide moderate relief since tissue hypoxia may be an underlying cause of the ulceration (Taher, Ismaeel and Cappellini, 2006; Gimmon, Wexler and Rachmilewitz, 1982).

Thrombophilia
Patients with thalassaemia intermedia have been shown to have an increased predisposition to thrombosis compared with thalassaemia major patients. Such events mainly occurred in the venous system and comprised deep vein thrombosis (40%), portal vein thrombosis (19%), stroke (9%), pulmonary embolism (12%) and others (20%). Moreover, splenectomised patients have been shown to have a higher risk of thrombosis than non-splenectomised patients (Cappellini, Robbiolo, Bottasso et al, 2000). (See Figure 2 for more on the thrombotic mechanism in thalassaemia intermedia.)

Management of thrombophilia has two arms: prevention and treatment. Prevention consists of proper anticoagulation prior to any surgical or other high-risk procedure. Treatment entails the adequate use of anticoagulation according to the recommendations for hypercoagulable states. Awareness is important since thromboembolism plays an important role in pulmonary hypertension and right heart failure (Taher, Ismaeel and Cappellini, 2006; Taher, Ismaeel, Mehio, Bignamini et al, 2006; Eldor, Rachmilewitz, 2002; Cappellini, Robbiolo, Bottasso et al, 2000; Taher, Abou- Mourad, Abchee et al, 2002).

Pulmonary hypertension and congestive heart failure
Pulmonary hypertension (PHT) is prevalent in patients with thalassaemia intermedia. In a study of 110 thalassaemia intermedia patients (60.9% untransfused or minimally transfused), 59.1% were shown to have PHT, which is thought to be the primary cause of congestive heart failure in this patient population (Aessopos, Farmakis, Karagiorga et al, 2001). The mechanism underlying pulmonary hypertension in thalassaemia intermedia is unclear. As anaemia and iron overload are uncommon in well-transfused and chelated thalassaemia major patients, the two conditions are likely to be at the root of the pathophysiology of pulmonary hypertension. Regular transfusion and iron chelation therapy is therefore indicated in thalassaemia intermedia patients who are well-stratified according to the early detection of pulmonary hypertension indices. Sildenafil has also been successfully used to treat pulmonary hypertension, although data from large patient numbers are lacking in thalassaemia intermedia (Taher, Ismaeel and Cappellini, 2006; Aessopos, Farmakis, Karagiorga et al, 2001; Aessopos, Farmakis, Deftereos et al, 2005).

Hepatitis
Hepatitis due to viral (B and C) infection is less frequent in thalassaemia intermedia than in patients with thalassaemia major, since blood transfusions are much less common in thalassaemia intermedia. Abnormal liver enzymes (increased alanine and aspartate aminotransferase) are frequently observed in patients with thalassaemia intermedia, primarily due to hepatocyte damage resulting from iron overload. Normalisation of liver enzyme levels is often observed during appropriate chelation therapy (Taher, Ismaeel and Cappellini, 2006; Cappellini, Cerino, Marelli and Fiorelli, 2001).

Endocrine function
Hypogonadism, hypothyroidism and diabetes mellitus are quite rare in thalassaemia intermedia. Although patients with thalassaemia intermedia generally experience puberty late, they have normal sexual development and are usually fertile. Hypothyroidism is sometimes observed late in life (Taher, Ismaeel and Cappellini, 2006; Cappellini, Cerino, Marelli and Fiorelli, 2001).

Pregnancy in TI
Women with thalassaemia intermedia may have spontaneous successful pregnancies, although complications during pregnancy may occur. The chronic anaemia of thalassaemia intermedia can cause an increase in spontaneous abortions, pre-term labour and intrauterine growth retardation, while endocrine complications due to haemosiderosis are common. Folic acid deficiency is common in thalassaemia intermedia and occurs due to poor absorption, low dietary intake or, most significantly, an increased demand for folic acid from active bone marrow. During pregnancy, women with thalassaemia intermedia should be given oral folic acid supplementation (around 1 mg/day), and should be carefully monitored in order to assess the need for transfusion therapy and to avoid haemodynamic compromises (Taher, Ismaeel and Cappellini, 2006; Nassar, Rechdan, Usta and Taher, 2006).

Iron overload
Just as in thalassaemia major, TI patients are susceptible to complications of iron overload. However, the mechanism involved in TI is increased absorption from the gut rather than blood transfusions. The resulting iron overload can lead to a number of serious complications, including cardiac failure and endocrine abnormalities such as diabetes mellitus and hypogonadism (Taher, Ismaeel and Cappellini, 2006; Weatherall, 2001). Initiation of iron chelation depends on the amount of excess iron, rate of iron accumulation, and duration of exposure to excess iron. Increased levels of liver iron concentration (LIC) have been observed with small increases in serum ferritin (Fiorelli, Fargion, Piperno et al, 1990). Thus, direct assessment of LIC by biopsy or MRI is recommended. Chelation therapy should be initiated if LIC ≥ 7 mg/g dry weight of liver (Taher, Ismaeel and Cappellini, 2006).

Osteoporosis
(also see chapter on osteoporosis)There is a high incidence of osteoporosis of the spine and hip in both sexes in thalassaemia intermedia. The severity increases with age and even young patients exhibit a spinal bone mineral density far below that of age-matched controls. Management consists of bisphosphonates and calcium supplementation with follow up bone-mass densitometries (Origa, Fiumana et al, 2005).

Pseudoxanthoma elasticum (PXE)
PXE is a rare hereditary connective tissue disorder, characterised by generalised degeneration of the elastic fibres with a broad phenotypic expression. The clinical picture consists mainly of cutaneous, ocular and vascular manifestations; skin histopathology involves swollen, irregularly clumped and multiply-fragmented elastic fibres in the middle and deep reticular dermis, with secondary calcium deposition. This condition has been described as occurring in Ùhalassaemia.

Management of thalassaemia intermedia
There are a number of options currently available for managing patients with thalassaemia intermedia, including splenectomy, transfusion therapy, modulation of fetal haemoglobin production and bone marrow transplantation (Taher, Ismaeel and Cappellini, 2006; Cappellini, Cerino, Marelli and Fiorelli, 2001).

Splenectomy
Splenectomy is no longer a major mode of management. However, the main indications for splenectomy include growth retardation or poor health, leucopenia, thrombocytopenia, increased transfusion demand and symptomatic splenomegaly. Splenectomy before the age of 5 carries a high risk of infection and is therefore not generally recommended.

Transfusion therapy and iron chelation
Although transfusion therapy is not currently a routine treatment approach for patients with thalassaemia intermedia, it can afford significant benefits. The decision to initiate therapy should be based on the presence and severity of signs and symptoms of anaemia, including failure of growth and development. As the rate of iron loading is variable in thalassaemia intermedia, an assessment of liver iron concentration is advisable before initiating transfusion therapy. Patients with thalassaemia intermedia may benefit from an individually tailored transfusion regimen, compared with the regular transfusion regimens implemented in thalassaemia major, to help prevent transfusion-dependency. Alloimmunisation is a relatively common observation in thalassaemia intermedia, although the risk is decreased if transfusion therapy is initiated before the age of 12 months (Pippard, Callender, Warner and Weatherall, 1979; Mourad, Hoffbrand, Sheikh- Taha et al, 2003; Cappellini, 2001).

Transfusions are indicated where the following are observed:
 * failure to thrive in childhood in the presence of significant anaemia;
 * emergence of bone deformities;
 * increasing anaemia not attributable to rectifiable factors;
 * evidence of a clinically relevant tendency to thrombosis;
 * presence of leg ulcers;
 * development of pulmonary hypertension;
 * delayed or poor pubertal growth spurt and
 * progressive splenic enlargement.

Modulation of fetal haemoglobin production
Increasing the synthesis of fetal haemoglobin can help to alleviate anaemia and thereby improve the clinical status of patients with thalassaemia intermedia. Agents including cytosine arabinoside and hydroxyurea may alter the pattern of erythropoiesis and increase the expression of Á-chain genes. Erythropoietin has been shown to be effective, with a possible additive effect in combination with hydroxyurea. Butyrates are a further experimental category, still unlicensed and with difficult intake. Good responses have been reported; however, most patients complain of the difficulty of intake orally and intravenously. Further clinical evaluation is required to clarify the value of this approach (Taher, Ismaeel and Cappellini, 2006; Karimi, H. Darzi, M. Yavarian, 2005; Dettelbach and Aviado, 1985; Dixit, Chatterjee, Mishra et al, 2005; Perrine, Ginder, Faller et al, 1993; Cappellini, Graziadei, Ciceri et al, 2000; Olivieri, Rees, Ginder et al, 1997). (For more details, see Chapter 13: Alternative approaches to the treatment of thalassaemia.)

Bone marrow
transplantation Bone marrow transplantation is an established treatment for ‚β-thalassaemia. Although marrow transplantation can lead to cure, the degree of its success depends primarily on the health and age of the patient. The decision as to which patients are eligible for transplantation is complex and is related to both quality of life and expected survival time of the transplanted patient. This is particularly relevant in patients with thalassaemia intermedia, especially in those who are only mildly affected. In stable asymptomatic TI patients who do not require transfusions, bone marrow transplantation is not needed.

Recommendations for the managemen of thalassaemia intermedia
Two major issues regarding the management of thalassaemia intermedia are 1) the approach and management of complications in adult thalassaemia intermedia patients and 2) preventing such complications in younger patients. A stratification of the management of TI between adults and young patients has therefore been established.

The scheme for adult thalassaemia intermedia patients is as follows:
 * each patient to be reviewed separately and stratified by risk;
 * hydroxyurea introduced as a suitable initial approach;
 * transfusion and iron chelation therapy with deferoxamine subcutaneous infusion and concomitant steroids for protection from alloimmunisation are essential;
 * aspirin for stroke prevention, postsplenectomy and life-long anticoagulation in patients with a history of thrombotic events is a must;
 * liver MRI assessment of iron concentration (or liver biopsy if MRI is unavailable) is important to determine liver iron status for future chelation.

There are no clear guidelines for the management of thalassaemia intermedia in the young. Thus, the authors recommend the following:

growth abnormalities, poor performance at school or a psychological impact secondary to facial deformities; therapy at earlier disease onset to prevent progression;
 * a guarded approach to the need for splenectomy and delay in initiating transfusion unless considered necessary based on the above mentioned indications;
 * early initiation of transfusion and iron chelation therapy if there is evidence of
 * regular follow-up with echocardiodoppler for cardiac complications and initiation of
 * regular follow up of liver iron concentration with MRI or liver biopsy;
 * discourage smoking, prolonged immobilisation and the use of oral contraceptives or an intrauterine device.

See Table 2 (page 130) for indications for transfusion and splenectomy.

Definition of β-thalassaemia/HbE
Haemoglobin E has the clinical phenotype of a mild form of β-thalassaemia, and is most frequent in southeast Asia, particularly eastern Thailand and Laos. The combination of HbE with β-thalassaemia spans thalassaemia phenotypes, from a condition indistinguishable from thalassaemia major to a mild form of thalassaemia intermedia (TIF, 2002; Premawardhena et al, 2005). Clinically, β-thalassaemia/HbE may be classified into three categories, each of which has its own unique clinical management requirements:

Mild β-thalassaemia/HbE
Mild β-thalassaemia/HbE patients do not require treatment and rarely develop clinical problems. Haemoglobin levels may be as high as 9-12 g/dl. Care should be taken not to confuse this group of patients with individuals having iron deficiency or with carriers of ‚-thalassaemia, by careful investigation of the red cell morphology, including iron status and haemoglobin electrophoresis (TIF, 2002; Premawardhena et al, 2005).

Moderately severe β-thalassaemia/HbE
This group encompasses the majority of β- thalassaemia/HbE patients. Most patients have steady haemoglobin levels of 6-7 g/dl. Clinically, these patients manifest symptoms similar to thalassaemia intermedia and normally do not require blood transfusions unless they develop infections precipitating further anaemia. Other complications such as iron overload may occur in these patients. Where this is the case, iron chelation therapy should be initiated. Patients in this group often have a somewhat shortened lifespan, but with careful monitoring and treatment can have an open-ended prognosis (TIF, 2002; Premawardhena et al, 2005).

Severe β-thalassaemia/HbE
Patients present with the clinical symptoms of thalassaemia major, including defective physical development, bone deformities including facial changes, anaemia, jaundice and hepatosplenomegaly. Haemoglobin levels can be as low as 4-5 g/dl. The clinical management of this group of patients needs to be addressed as in thalassaemia major (TIF, 2002; Premawardhena et al, 2005).

Complications and management of β-thalassaemia/HbE
Complications in β-thalassaemia/HbE patients depend on the category they belong to, as indicated above. The worst of the complications occur in the severe group, in which the clinical picture is similar to that β- thalassaemia major. This includes the multitude of problems brought about by iron overload due to dependence on transfusions (see sections on complications in β- thalassaemia major for further explanation).