Gaucher Disease Diagnosis Using Lyso-Gb1 on Dry Blood Spot Samples: Time to Change the Paradigm?

For years, the gold standard for diagnosing Gaucher disease (GD) has been detecting reduced ß-glucocerebrosidase (GCase) activity in peripheral blood cells combined with GBA1 mutation analysis. The use of dried blood spot (DBS) specimens offers many advantages, including easy collection, the need for a small amount of blood, and simpler transportation. However, DBS has limitations for measuring GCase activity. In this paper, we recount our cross-sectional study and publish seven years of experience using DBS samples and levels of the deacylated form of glucocerebroside, glucosylsphingosine (lyso-Gb1), for GD diagnosis. Of 444 screened subjects, 99 (22.3%) were diagnosed with GD at a median (range) age of 21 (1-78) years. Lyso-Gb levels for genetically confirmed GD patients vs. subjects negative to GD diagnosis were 252 (9-1340) ng/mL and 5.4 (1.5-16) ng/mL, respectively. Patients diagnosed with GD1 and mild GBA1 variants had lower median (range) lyso-Gb1, 194 (9-1050), compared to GD1 and severe GBA1 variants, 447 (38-1340) ng/mL, and neuronopathic GD, 325 (116-1270) ng/mL (p = 0.001). Subjects with heterozygous GBA1 variants (carrier) had higher lyso-Gb1 levels, 5.8 (2.5-15.3) ng/mL, compared to wild-type GBA1, 4.9 (1.5-16), ng/mL (p = 0.001). Lyso-Gb1 levels, median (range), were 5 (2.7-10.7) in heterozygous GBA1 carriers with Parkinson's disease (PD), similar to lyso-Gb1 levels in subjects without PD. We call for a paradigm change for the diagnosis of GD based on lyso-Gb1 measurements and confirmatory GBA1 mutation analyses in DBS. Lyso-Gb1 levels could not be used to differentiate between heterozygous GBA1 carriers and wild type.

Oxidative Stress Parameters, Trace Elements, and Lipid Profile in Iranian Patients with Gaucher Disease.

Gaucher disease (GD) is most frequent disorder of glycolipid storage. The glucosylceramide accumulation might lead to oxidative stress and changes in lipid profile. Regarding the main role of trace elements in hematopoiesis and oxidative stress, this study was aimed to evaluate the zinc and copper levels, three oxidative stress parameters, and lipid profile in GD. Thirty-three patients with GD along with 64 age- and sex-matched healthy controls participated in the study. The levels of zinc and copper were determined using atomic absorption/flame emission spectrophotometer. Malondialdehyde level was measured using HPLC. Total antioxidant capacity (TAC), catalase activity, and lipid profile were assessed using colorimetric methods. Data were analyzed using SPSS software version 16.0. Significant decrease in the serum levels of Zn (p < 0.001) and Cu (p < 0.001) was observed in patients with GD compared to controls. Subjects in control group showed significantly higher levels of TAC than patients with GD (p < 0.001). In contrast, plasma concentration of malondialdehyde was insignificantly higher in patients with GD than controls (p = 0.06). There was a direct correlation between TAC and hemoglobin concentration (p = 0.035; r = 0.369) in patients with GD. Furthermore, the calculated area under receiver operating characteristic curve for HDL cholesterol was equal to 0.938. The results showed that both zinc and copper levels decreased in patients with GD. Patients with GD showed decreased serum content of TAC. It was found that improving the deficiency of zinc and copper by supplementing them could be useful in management of patients with GD.

Neuronopathic Gaucher disease presenting with microcytic hypochromic anemia.

Gaucher disease (GD) is caused by a hereditary deficiency of glucocerebrosidase, resulting in accumulation of glucosylceramide and potentially manifesting as hepatosplenomegaly. We report the case of a 15-month-old boy with chronic neuronopathic GD. The patient had prolonged anemia despite continued iron supplementation for 3 months. White blood count (WBC), hemoglobin (Hb), platelet count, and corrected reticulocyte count were 3,300 /µL, 8.7 g/dL, 90,000 /µL, and 0.55, respectively. The patient had microcytic hypochromic anemia with mildly elevated ferritin. Physical examination revealed hepatosplenomegaly. Bone-marrow aspiration showed sheets of Gaucher cells. Glucocerebrosidase activity in monocytes was significantly lower than normal. Genetic analysis revealed a homozygous L444P mutation of GBA, and he was diagnosed with type 1 GD. Enzyme replacement treatment (ERT) consisting of imiglucerase was initiated and was effective; WBC, Hb, and platelet count gradually normalized and the hepatosplenomegaly improved. However, when the patient entered elementary school, he showed mild impaired cognitive function, and supranuclear gaze palsy occurred the same year. He was ultimately diagnosed with type 3 GD and continued ERT. Pediatric hemato-oncologists should be aware of GD, especially when patients exhibit anemia refractory to iron therapy, radiologic bone deformity, neurologic signs or symptoms, and growth retardation.

Twelve years of experience with miglustat in the treatment of type 1 Gaucher disease: The Spanish ZAGAL project.

We report data from a prospective, observational study (ZAGAL) evaluating miglustat 100mg three times daily orally. in treatment-naïve patients and patients with type 1 Gaucher Disease (GD1) switched from previous enzyme replacement therapy (ERT). Clinical evolution, changes in organ size, blood counts, disease biomarkers, bone marrow infiltration (S-MRI), bone mineral density by broadband ultrasound densitometry (BMD), safety and tolerability annual reports were analysed. Between May 2004 and April 2016, 63 patients received miglustat therapy; 20 (32%) untreated and 43 (68%) switched. At the time of this report 39 patients (14 [36%] treatment-naïve; 25 [64%] switch) remain on miglustat. With over 12-year follow-up, hematologic counts, liver and spleen volumes remained stable. In total, 80% of patients achieved current GD1 therapeutic goals. Plasma chitotriosidase activity and CCL-18/PARC concentration showed a trend towards a slight increase. Reductions on S-MRI (p=0.042) with an increase in BMD (p<0.01) were registered. Gastrointestinal disturbances were reported in 25/63 (40%), causing miglustat suspension in 11/63 (17.5%) cases. Thirty-eight patients (60%) experienced a fine hand tremor and two a reversible peripheral neuropathy. Overall, miglustat was effective as a long-term therapy in mild to moderate naïve and ERT stabilized patients. No unexpected safety signals were identified during 12-years follow-up.

Enzyme replacement and substrate reduction therapy for Gaucher disease.

BACKGROUND: Gaucher disease, a rare disorder, is caused by inherited deficiency of the enzyme glucocerebrosidase. It is unique among the ultra-orphan disorders in that four treatments are currently approved by various regulatory authorities for use in routine clinical practice. Hitherto, because of the relatively few people affected worldwide, many of whom started therapy during a prolonged period when there were essentially no alternatives to imiglucerase, these treatments have not been systematically evaluated in studies such as randomized controlled trials now considered necessary to generate the highest level of clinical evidence. OBJECTIVES: To summarize all available randomized controlled study data on the efficacy and safety of enzyme replacement therapies and substrate reduction therapy for treating Gaucher disease. SEARCH METHODS: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Inborn Errors of Metabolism Trials Register. Additional searches were conducted on ClinicalTrials.gov for any ongoing studies with potential interim results, and through PubMed. We also searched the reference lists of relevant articles and reviews.Date of last search: 07 August 2014. SELECTION CRITERIA: All randomized and quasi-randomized controlled studies (including open-label studies and cross-over studies) assessing enzyme replacement therapy or substrate reduction therapy, or both, in all types of Gaucher disease were included. DATA COLLECTION AND ANALYSIS: Two authors independently assessed the risk of bias in the included studies, and extracted relevant data. MAIN RESULTS: Of the 488 studies retrieved by the electronic searches, eight met the inclusion criteria and were analysed (300 participants). Response parameters were restricted to haemoglobin concentration, platelet count, spleen and liver volume and serum biomarkers (chitotriosidase and CCL18). Only one publication reported a 'low risk of bias' score in all parameters assessed, and all studies included were randomized.Four studies reported the responses to enzyme replacement therapy of previously untreated individuals with type 1 Gaucher disease. Two studies investigated maintenance enzyme replacement therapy in people with stable type 1 Gaucher disease previously treated for at least two years. One study compared substrate reduction therapy, enzyme replacement therapy and a combination thereof as maintenance therapy in people with type 1 Gaucher disease previously treated with enzyme replacement therapy. One study examined substrate reduction therapy in people with chronic neuronopathic (type 3) Gaucher disease who continued to receive enzyme replacement therapy.Treatment-naïve participants had similar increases in haemoglobin when comparing those receiving imiglucerase or alglucerase at 60 units/kg, imiglucerase or velaglucerase alfa at 60 U/kg, taliglucerase alfa at 30 units/kg or 60 units/kg, and velaglucerase alfa at 45 units/g or 60 units/kg. For platelet count response in participants with intact spleens, a benefit for imiglucerase over velaglucerase alfa at 60 units/kg was observed, mean difference -79.87 (95% confidence interval -137.57 to -22.17). There were no other significant differences in platelet count response when comparing different doses of velaglucerase alfa and of taliglucerase alfa, and when comparing imiglucerase to alglucerase. Spleen and liver volume reductions were not significantly different in any enzyme replacement therapy product or dose comparison study. Although a dose effect on serum biomarkers was not seen after nine months, a significantly greater reduction with higher dose was reported after 12 months in the velaglucerase study, mean difference 16.70 (95% confidence intervaI 1.51 to 31.89). In the two enzyme replacement therapy maintenance studies comparing infusions every two weeks and every four weeks, there were no significant differences in haemoglobin concentration, platelet count, and spleen and liver volumes over a 6 to 12 month period when participants were treated with the same cumulative dose.A total of 25 serious adverse events were reported, nearly all deemed unrelated to treatment.There are, as yet, no randomized trials of substrate reduction therapy in treatment-naïve patients that can be evaluated. Miglustat monotherapy appeared as effective as continued enzyme replacement therapy for maintenance of hematological, organ and biomarker responses in people with type 1 Gaucher disease previously treated with imiglucerase for at least two years. In those with neuronopathic Gaucher disease, no significant improvements in haemoglobin concentration, platelet count or organ volumes occurred when enzyme replacement therapy was augmented with miglustat.One randomized controlled study assessing substrate reduction therapy was published immediately prior to producing the final version of this review, and this, along with a further ongoing study (expected to be published in the near future), will be assessed for eligibility in a future update of the review. AUTHORS' CONCLUSIONS: The results reflect the limitations of analysing evidence restricted to prospective randomized controlled trials, especially when dealing with chronic rare diseases. This analysis suggests that, during the first year of treatment, different recombinant glucocerebrosidases are bio-similar and non-inferior in safety and efficacy for surrogate biological response parameters. Enzyme replacement therapy given at 30 to 45 units/kg body weight every two to four weeks was generally as effective as the 60 unit/kg dose for the assessed clinical outcomes. The analysis emphasise the need to determine whether it is realistic to carry out multi-decade prospective clinical trials for rare diseases such as type 1 Gaucher disease. With large treatment effects on the classical manifestations of the disorder, therapeutic investigations in Gaucher disease mandate innovative trial designs and methodology to secure decisive data concerning long-term efficacy and safety - with the realization that knowledge about disease-modifying actions that are sustained are of crucial importance to people with this chronic condition.

Oxidative stress, trace elements, and circulating microparticles in patients with Gaucher disease before and after enzyme replacement therapy.

UNLABELLED: We studied the level of lipid peroxide, nitric oxide (NO), trace elements (TEs), and microparticles (MPs) in Gaucher disease (GD) before and after 1 year of enzyme replacement therapy (ERT). A total of 15 children with GD and 15 healthy controls were enrolled in this study. Serum level of lipid peroxide, NO, and TEs was determined. The MPs were detected by flow cytometry. The level of lipid peroxide was significantly higher in the patients than in the controls even after ERT. Although NO level was normalized in the patients after ERT, zinc and copper were still lower in the patients after ERT. The percentages of various MPs were significantly higher in the patients than in the controls both before and after ERT. There were positive correlations between chitotriosidase and both lipid peroxide and total MPs. CONCLUSION: The GD is associated with alteration in oxidant and antioxidant status and high level of circulating MPs.

Miglustat therapy in type 1 Gaucher disease: clinical and safety outcomes in a multicenter retrospective cohort study.

We evaluated clinical and safety outcomes in adult patients with type 1 Gaucher disease receiving miglustat in clinical practice settings. An observational, retrospective cohort study was conducted in centers across the EU and the USA. Medical chart data were collected from consecutive patients between the 20th November 2002 and 31st December 2008. A total of 115 patients were included; 34 (30%) were enzyme replacement therapy-naïve ('naïve') and 81 (70%) were enzyme pretreated ('pretreated'). Median (range) miglustat exposures in these groups were 15.1 (0.6-52.9)months and 15.2 (0.3-62.1)months, respectively. Low numbers of patients were anemic (10/101) or thrombocytopenic (21/101) at initiation of miglustat therapy. The median (range) hemoglobin concentration at miglustat initiation was 12.8 (10.2-16.4)g/dl in naïve patients and 13.6 (7.3-17.4)g/dl in pretreated patients; median (range) changes in hemoglobin were 0.3 (-2.5-3.6) and -0.3 (-4-4.6)g/dl, respectively. The median (range) platelet counts at miglustat initiation were 101 (37-730)×10(9)/l in naïve patients and 173 (43-382)×10(9)/l in pretreated patients; median (range) changes in platelet count were 8 (-77-145)×10(9)/l and -10 (-144-434)×10(9)/l, respectively. Plasma chitotriosidase was substantially reduced in naïve but not in pretreated patients. Organ volumes were not routinely monitored. Forty-nine (43%) patients discontinued miglustat; most due to gastrointestinal manifestations and some due to tremor. Overall, hemoglobin and platelet counts tended to increase in naïve patients treated with miglustat, and to remain stable or decrease slightly in pretreated patients. The profile of safety and tolerability observed with miglustat in the current study is similar to previous studies.

Velaglucerase alfa for the management of type 1 Gaucher disease.

BACKGROUND: Gaucher disease (GD) is the most common lysosomal storage disease, (frequency of 1:40,000 to 1:60,000). Ninety-Five percent of patients have type 1 (nonneuropathic type). Symptomatic patients with type 1 GD are treated with enzyme replacement therapy (ERT) to improve disease-induced effects on hemoglobin, platelets, and liver and spleen volume. Currently, several ERTs are available. OBJECTIVE: The goal of this article was to review the pharmacology, efficacy, and safety data available for the use of a recently approved ERT, velaglucerase alfa, for the treatment of type 1 GD in symptomatic pediatric and adult patients. METHODS: Serial searches of MEDLINE, EMBASE, and Cochrane databases for English-language, peer-reviewed, clinical data (using the search term velaglucerase alfa) were completed, with the final search in November 2011. All identified, peer-reviewed published human data were used for this review. Due to minimal peer-reviewed published data, those data reported via clinical trial registries or in the form of published abstracts were included. The manufacturer was contacted and given the opportunity to submit supplemental data for consideration of inclusion by the author. RESULTS: Velaglucerase alfa is produced through gene activation technology and is identical to wild-type enzyme. As with other ERTs for type 1 GD, velaglucerase alfa targets accumulated glucocerebroside primarily within the lysosome of the macrophages in the affected organs and systems. When administered at doses of 60 U/kg intravenously, velaglucerase alfa follows linear pharmacokinetics and is rapidly eliminated, with a mean (SD) residence time or time for 63% of the dose to be cleared from systemic circulation of 14 (4) minutes. Four trials and early access program data reporting efficacy were identified for this review: 5 peer-reviewed publications, 3 clinical trial registry reports, and 1 abstract-only publication. Phase I/II data with an extension phase (n = 12) showed significant improvements (all, P < 0.004) in hemoglobin concentrations (21.7%), platelet counts (157.8%), and hepatic (-42.8%) and spleen (-79.3%) volumes at 48 months. Bone mineral density data reported out to 69 months for this extension population noted significant improvements in z score slope for both lumbar spine (0.14 z score unit per year; P < 0.01) and femoral head (0.08 z score unit per year; P < 0.01). Benchmarking of 7 patients with complete clinical datasets at 57 months identified achievement and maintenance of therapeutic goals set by the International Collaborative Gaucher Group for anemia, platelet counts, hepatosplenomegaly, and bone mineral density. Thirty-eight patients enrolled in an open-label, therapy-switch trial who received velaglucerase alfa at doses consistent with current doses of imiglucerase maintained hemoglobin (-0.101 g/dL [95% CI, -0.272 to 0.07]) and platelet counts (7.04% [95% CI, 0.54% to 13.53%]) at 53 weeks after therapy change. Phase III data evaluating 2 dosing regimens of velaglucerase alfa 60 and 45 U/kg intravenously every other week reported significant improvements in most measured clinical parameters at 12 months: hemoglobin concentrations (60 U/kg, 2.429 [0.324] g/dL [P < 0.0001]; 45 U/kg, 2.438 g/dL [95% CI, 1.488 to 3.389]), platelet counts (60 U/kg, 50.88 × 10(9)/L [95% CI, 23.97 to 77.78]; 45 U/kg, 40.92 × 10(9)/L [95% CI, 11.2 to 70.64]), spleen volumes (60 U/kg, -1.92% of body weight [95% CI, -3.04 to -0.79]; 45 U/kg, -1.87% of body weight [95% CI, -3.17 to -0.57]), and hepatic volumes (60 U/kg, -0.84% of body weight [95% CI, -1.58 to -0.11]). A subanalysis of the pediatric population showed clinical improvements at 12 months in both dosing groups: hemoglobin concentrations (60 U/kg, 1.74 g/dL [95% CI, 0.72 to 2.78]; 45 U/kg, 2.77 g/dL [95% CI, -0.99 to 6.53]), platelet counts (60 U/kg, 49.9 × 10(9)/L [95% CI, -32.1 to 131.9]; 45 U/kg, 60.3 × 10(9)/L [95% CI, -103.1 to 223.7]), spleen volumes (60 U/kg, -2.1 cm(3) [95% CI, -5.3 to 1.1]; 45 U/kg, -0.7 cm(3) [95% CI, -2.6 to 1.2]), and hepatic volumes (60 U/kg, -0.7 cm(3) [95% CI, -1.4 to 0.0]; 45 U/kg, -0.3 cm(3) [95% CI, -1.7 to 1.1]). Data comparing velaglucerase alfa with imiglucerase identified similar changes in hemoglobin concentrations at 1.624 g/dL and 1.488 g/dL, respectively, after 9 months of therapy. Safety was reported in 3 identified studies and in data reported from the early access program: 3 peer-reviewed publications, 3 studies reported in clinical trial registries, and 1 abstract publication. Patients experienced a minimal number of adverse effects, and most reactions were mild to moderate in severity; 1 patient developed an anaphylactoid reaction and was discontinued from the trial. Antibody formation has been described with velaglucerase alfa but when compared with that of imiglucerase, seroconversion is less frequent (1% and 23%, respectively). Dosing regimens, from 30 to 60 U/kg intravenously every other week, have been assessed. Currently, the manufacturer recommends 60 U/kg intravenously every other week; however, further studies and evaluation of current study dosing regimens are needed to determine if there is a lower effective dose. CONCLUSIONS: Although a minimal amount of data are available for this relatively new biological agent, velaglucerase alfa reportedly is effective in the achievement and maintenance of therapeutic goals in type 1 GD in both treatment-naive and patients previously treated with imiglucerase. This agent has been reasonably well tolerated in clinical trials and may be considered for use in symptomatic patients with type 1 GD.

Patients with Gaucher disease living in England show a high prevalence of vitamin D insufficiency with correlation to osteodensitometry.

AIM: Gaucher disease type 1 (GD-1) is the most prevalent lysosomal storage disorder and frequently causes osteopenia and osteoporosis. Adequate vitamin D levels are essential for bone health. The present study retrospectively analyzed 25-hydroxyvitamin D (25[OH]D) in outpatients with GD-1. PATIENTS AND METHODS: Sixty GD-1 patients living at home and with residence in southern or central England (34 men, 26 women), aged 17-85 years (mean 45.0 years) were seen at routine follow-up visits (range: 1-9, mean: 4.4) between January 2003 and July 2007. Overall, 264 blood samples, collected at different seasons of the year, were present for laboratory testing. The retrospective interpretation of vitamin D deficiency was based on different cut-off levels of 25(OH)D (<25 nmol/L, <50 nmol/L, <80 nmol/L) and the seasons of the year. Vitamin D sufficiency was defined as 25(OH)D >80 nmol/L. RESULTS: The mean+/-SD of 25(OH)D was 58.2+/-30.3. Degrees of vitamin D deficiency (<25 nmol/L, <50 nmol/L, <80 nmol/L) were present in 9.1%, 44.3%, 83.0%, vitamin D sufficiency (>80 nmol/L) in only 17.0%, respectively. A significant seasonal variation of 25(OH)D was present. Results of vitamin D deficiency for December-May were 15.7%, 63.8%, 92.9%, and for June-November 2.9%, 26.3%, 73.7%. The 25(OH)D values representing the seasonal nadir observed during the season December-May showed a significant correlation with T-scores and Z-scores of the lumbar spine and hip. Parathyroid hormone and 25(OH)D were inversely correlated. CONCLUSIONS: Vitamin D deficiency is frequent among GD-1 patients. To optimize treatment of GD-1 vitamin D supplementation should be recommended.

Effective treatment of an elderly patient with Gaucher's disease and Parkinsonism: a case report of 24 months' oral substrate reduction therapy with miglustat.

We report here the results of 24 months' treatment with oral miglustat of a patient with mild-to-moderate Gaucher's disease (GD) and Parkinsonism. The patient's progressive Parkinsonian tremor, in addition to restricted vascular access, necessitated switching treatment for GD from intravenously infused enzyme replacement therapy (ERT) that had been administered for the previous 7 years. With control of haematological parameters and markers of GD activity improved or maintained and no notable adverse effects, miglustat treatment proved an effective and well-tolerated therapeutic alternative to ERT. Oral miglustat should be considered for the treatment of patients with type I GD and concurrent movement disorders who are unsuitable for ERT.

Elevated plasma chemokine CCL18/PARC in beta-thalassemia.

Plasma CCL18/PARC, a member of the CC chemokine family, has been found to be several ten-fold increased in symptomatic Gaucher type I patients. Elevated plasma chitotriosidase levels are a well-known abnormality in Gaucher patients, however, its diagnostic use is limited by the frequent genetic deficiency in the protein. Like the situation in Gaucher disease, lipids accumulate in macrophages of patients suffering from beta-thalassemia, and, in both conditions, increased chitotriosidase levels occur. We here report that plasma CCL18/PARC is also significantly increased in patients with beta-thalassemia major (range 76.8-4977.8, median=650.8 ng/ml, n=36 and control range 10-72, median=33 ng/ml n=36 respectively, P<0.001). The CCL18/PARC levels are lower than in Gaucher patients (range 174.8-10798.7, median 2538.2 ng/ml, n=28, P<0.001). In our cohort of beta-thalassemic patients, CCL18/PARC showed a significant negative correlation to iron chelation therapy and a significant positive correlation to ferritin and chitotriosidase levels, the latter only in the patients with the wild type genotype for the enzyme. Our study demonstrates that beta-thalassemic patients have increased CCL18/PARC levels that could be of value in monitoring iron overload and compliance to therapy.

Plasma chitotriosidase activity in patients with beta-thalassemia.

Chitotriosidase, a macrophage marker, which is extremely increased in plasma of Gaucher patients, was measured in patients with beta-thalassemia, an haematological disorder characterized by the genetic defect of beta-globin chains synthesis resulting in unproductive erythropoiesis and enormous expansion of the reticuloendothelial system. Plasma chitotriosidase was increased to a variable extent in 13 of 70 patients with beta-thalassemia major treated with the intense transfusion regimen and iron chelation therapy. It was normal in 22 and slightly elevated in 3 subjects with beta-thalassemia intermedia which were not transfused. The highest levels of plasma chitotriosidase, as high as in Gaucher patients, were found in 7 (10%) of the beta-thalassemia major patients which also had the highest degree of iron overload as judged by their serum ferritin level (> 3000 ng/ml), high SGPT level and elevated urinary iron excretion. To our knowledge, beta-thalassemia is hitherto the only disorder in which an increase of plasma chitotriosidase, comparable to that seen in Gaucher disease, may occur. The increase of plasma chitotriosidase activity in beta-thalassemia patients with high iron overload, could be related to an iron mediated damage to the lysosomal apparatus. In addition, similarly to Gaucher disease, the increased chitotriosidase production in beta-thalassemia might reflect macrophage activation probably related to the intracellular iron overload, storage of erythrocytes membrane break-down products and oxidation of excess alpha-hemoglobin subunits. Further studies are required to define the role of chitotriosidase evaluation to assess the efficacy of chelation therapy in reducing the macrophage activation due to intracellular iron overload in beta-thalassemia.