Pakawan Wongwerawattanakoon

The use of rituximab as an adjuvant for immune tolerance therapy in a hemophilia B boy with inhibitor and anaphylaxis to factor IX concentrate.

We describe a 10-year-old severe hemophilia B boy with a stop codon mutation of exon 2 in the factor IX gene who developed high inhibitor of 70 Bethesda units (BU) from 12 months of age after exposure to prothrombin complex concentrate for 14 days. The inhibitor spontaneously disappeared within 3 months. The patient, however, exhibited anaphylactic reaction to the administration of prothrombin complex concentrate and factor IX concentrate at ages 15 and 23 months, respectively. Although recombinant activated factor VII was alternatively given, he suffered from progressive hemophilic arthropathy. At the age of 10 years, the boy underwent desensitization to factor IX concentrate and could tolerate factor IX concentrate of 40 U/kg administered on day 9 of desensitization. Unfortunately, the inhibitor of 16 BU was detected on day 6 and rapidly increased to 180 BU on day 9 of desensitization. Rituximab 375 mg/m2 per week was therefore immediately initiated on day 10 and a total of four doses were given. The inhibitor gradually decreased to 21.5 BU after the fourth dose of rituximab. The daily factor IX concentrate administration of 40 U/kg was continued for 1 month and decreased to three times per week for another month, and then to once to twice per week for the remaining 14 months of desensitization. The patient was able to attend regular school and the most recent inhibitor ranged from 4.4 to 10 BU. No proteinuria or alteration of renal function was found. In conclusion, rituximab is a helpful adjuvant to immune tolerance therapy in a hemophilia B boy with inhibitor and anaphylaxis to factor IX concentrate.

Combined Chelation Therapy with Daily Oral Deferiprone and Twice-Weekly Subcutaneous Infusion of Desferrioxamine in Children with β-Thalassemia: 3-Year Experience

Objective: To study the efficacy of combined treatment with oral and subcutaneous iron chelators. Material and Methods: 50-100 mg/kg/day of oral deferiprone (DFP) combined with 40 mg/kg/dose s.c. desferrioxamine (DFO) twice weekly were given to transfusion-dependent β-thalassemia children. Results: Enrolled patients (9 with β-thalassemia major and 33 with β-thalassemia hemoglobin E), ranging from 3 to 18 years in age, were divided into 3 groups; group 1 ferritin ≥1,000-2,500 ng/ml (n = 10), group 2 ferritin >2,500-4,000 ng/ml (n = 23) and group 3 ferritin >4,000 ng/ml (n = 9). Of the 42 patients, 28 reached the 36-month follow-up. Ten patients whose ferritin declined <15% while receiving 100 mg/kg/day of DFP were considered nonresponders. The median age and previous transfusion duration before enrollment were significantly higher in nonresponders than responders (p = 0.04 and 0.003, respectively). The responders exhibited a significant fall in median ferritin levels from 2,954.6 to 936.6 ng/ml (p < 0.001). Time to a significant decrease in serum ferritin among responders was 6 months. In 13 patients, 16 episodes of adverse events occurred: hemophagocytosis with cytopenia (n = 1), neutropenia (n = 2), thrombocytopenia (n = 2), elevated alanine aminotransferase (n = 5), elevated serum creatinine (n = 1), proteinuria (n = 1) and gastrointestinal discomfort (n = 4). Conclusion: Combination therapy with daily oral DFP and subcutaneous DFO twice weekly is a safe and effective alternative to chelation monotherapy in β-thalassemia children.

Safety profile of a liquid formulation of deferiprone in young children with transfusion-induced iron overload: a 1-year experience

Background: Data on the use of deferiprone in young children with iron overload are limited. Objective: To study the safety profile of a liquid formulation of deferiprone in chelating young children with transfusion-induced iron overload. Patients and methods: A daily dose of 50–100 mg/kg BW in three divided doses of oral deferiprone was given to young patients who had received at least ten packed red cell transfusions and achieved a serum ferritin level >1000 μg/L during a 12-month period from 2011 to 2012. Results: Nine children (four males) diagnosed with various types of thalassaemia (n = 8) and hereditary spherocytosis (n = 1) were enrolled. Their mean (SD) age was 4.5 (1.9) years. The patients received 15–20 ml/kg BW of packed red cell transfusions every 4–8 weeks from a mean (SD) age of 2.1 (1.7) years to maintain a pre-transfusion haematocrit at 27%. A mean (SD) total of packed red cells of 5132 (2725) ml were given within a mean (SD) duration of 2.4 (1.1) years before the study. During the 1-year study period, they received a mean (SD) total of packed red cells of 2194 (680) ml or 138 (50) ml/kg BW with a mean (SD) daily iron load of 0.29 (0.12) mg/kg BW. The pre-treatment geometric mean of serum ferritin of 1863.8 μg/L decreased to 1279.7 μg/L after 1 year of treatment (P = 0.05). All patients tolerated the liquid formulation well and did not experience any gastro-intestinal discomfort, nausea or vomiting. Conclusion: The liquid formulation of deferiprone is safe in young children with transfusion-induced iron overload.BACKGROUND Data on the use of deferiprone in young children with iron overload are limited. OBJECTIVE To study the safety profile of a liquid formulation of deferiprone in chelating young children with transfusion-induced iron overload. PATIENTS AND METHODS A daily dose of 50-100 mg/kg BW in three divided doses of oral deferiprone was given to young patients who had received at least ten packed red cell transfusions and achieved a serum ferritin level >1000 μg/L during a 12-month period from 2011 to 2012. RESULTS Nine children (four males) diagnosed with various types of thalassaemia (n = 8) and hereditary spherocytosis (n = 1) were enrolled. Their mean (SD) age was 4.5 (1.9) years. The patients received 15-20 ml/kg BW of packed red cell transfusions every 4-8 weeks from a mean (SD) age of 2.1 (1.7) years to maintain a pre-transfusion haematocrit at 27%. A mean (SD) total of packed red cells of 5132 (2725) ml were given within a mean (SD) duration of 2.4 (1.1) years before the study. During the 1-year study period, they received a mean (SD) total of packed red cells of 2194 (680) ml or 138 (50) ml/kg BW with a mean (SD) daily iron load of 0.29 (0.12) mg/kg BW. The pre-treatment geometric mean of serum ferritin of 1863.8 μg/L decreased to 1279.7 μg/L after 1 year of treatment (P = 0.05). All patients tolerated the liquid formulation well and did not experience any gastro-intestinal discomfort, nausea or vomiting. CONCLUSION The liquid formulation of deferiprone is safe in young children with transfusion-induced iron overload.

Protein C deficiency in Thai children with thromboembolism: A report of clinical presentations and mutation analysis.

Protein C, a natural anticoagulant, has been reported to be a common thrombophilic risk factor in Thai and other Asian populations [1,2]. Patients with protein C deficiency mainly present with venous rather than arterial thromboembolism [3,4]. Protein C deficiency has an autosomal dominant pattern of inheritance. It is classified into two types; type 1, characterized by decreased plasma concentrations of both protein C activity and antigen and type 2, characterized by decreased protein C activity but normal plasma concentration of protein C antigen. The prevalence of protein C deficiency in healthy Thai population and patients with venous thromboembolism was reported as 2% and 8.9%, respectively, higher than Caucasians [5–7]. To date, over 300 mutations have been reported [8]. Significant differences in protein C mutations identified in different ethnicities were seen, for example, the R230C, Q132X, R306X and 3363insC mutations were commonly found in Caucasian populations [9,10] while R147W was a common mutation among Taiwanese Chinese [11]. We report the clinical presentations and mutation analysis of six Thai children with protein C deficiency. Protein C activity and antigen were tested at the time of diagnosis and repeated three months after thromboembolic events or at the time of anticoagulant discontinuation and at the age of five years. The polymerase chain reaction (PCR) amplifications of exon 1 to 9 were performed using our own designed primers (Table 1), and then mutations were screened by using conformation sensitive gel electrophoresis (CSGE), a heteroduplexbased method for nucleotide mismatch detection of all exons [12]. Samples displaying abnormal CSGE pattern were subjected to sequencing. Nucleotide and amino acid numbering was referenced to Foster et al [13].

Correlation between liver iron concentration determined by magnetic resonance imaging and serum ferritin in adolescents with thalassaemia disease

Background: MRI imaging is an alternative to serum ferritin for assessing iron overload in patients with thalassaemia disease. Aims: To correlate liver iron concentration (LIC) determined by MRI and clinical and biochemical parameters. Methods: An MRI study using cardiovascular magnetic resonance (CMR) tools to determine cardiac and liver iron was undertaken in adolescents with thalassaemia disease. Results: Eighty-nine patients (48 males) with thalassaemia disease were enrolled. Seventy patients had been transfusion-dependent since a mean (SD) age of 3.8 (3.0) years, and 19 patients were not transfusiondependent. Mean (SD) haematocrit was 27.3 (2.9)%. Twenty-eight patients were splenectomized. Mean (SD) serum ferritin was 1673 (1506) μg/L. All transfusion-dependent patients received iron chelation at the mean (SD) age of 8.4 (3.5) years with either monotherapy of desferrioxamine, deferiprone, deferasirox or combined therapy of desferrioxamine and deferiprone, while only 5 of 19 patients who were not transfusion-dependent received oral chelation. The 89 patients underwent an MRI scan at the mean (SD) age of 14.8 (3.2) years. No patients had myocardial iron overload, but nine had severe liver iron overload, 27 had moderate liver iron overload, and 36 had mild liver iron overload. A significant correlation between liver T2* and serum ferritin was expressed as the equation: T2* (ms) = 28.080–7.629 log ferritin (μg/L) (r2 0.424, P = 0.0001). Patients with serum ferritin of >1000 to >2500 μg/L risked moderate and severe liver iron loading with the odds ratio ranging from 6.8 to 13.3 (95% CI 2.5–50.8). Conclusion: In thalassaemia, MRI is an alternative means of assessing iron stores, but when it is not available serum ferritin can be used to estimate liver T2*.BACKGROUND MRI imaging is an alternative to serum ferritin for assessing iron overload in patients with thalassaemia disease. AIMS To correlate liver iron concentration (LIC) determined by MRI and clinical and biochemical parameters. METHODS An MRI study using cardiovascular magnetic resonance (CMR) tools to determine cardiac and liver iron was undertaken in adolescents with thalassaemia disease. RESULTS Eighty-nine patients (48 males) with thalassaemia disease were enrolled. Seventy patients had been transfusion-dependent since a mean (SD) age of 3.8 (3.0) years, and 19 patients were not transfusiondependent. Mean (SD) haematocrit was 27.3 (2.9)%. Twenty-eight patients were splenectomized. Mean (SD) serum ferritin was 1673 (1506) μg/L. All transfusion-dependent patients received iron chelation at the mean (SD) age of 8.4 (3.5) years with either monotherapy of desferrioxamine, deferiprone, deferasirox or combined therapy of desferrioxamine and deferiprone, while only 5 of 19 patients who were not transfusion-dependent received oral chelation. The 89 patients underwent an MRI scan at the mean (SD) age of 14.8 (3.2) years. No patients had myocardial iron overload, but nine had severe liver iron overload, 27 had moderate liver iron overload, and 36 had mild liver iron overload. A significant correlation between liver T2* and serum ferritin was expressed as the equation: T2* (ms) = 28.080-7.629 log ferritin (μg/L) (r(2) 0.424, P = 0.0001). Patients with serum ferritin of >1000 to >2500 μg/L risked moderate and severe liver iron loading with the odds ratio ranging from 6.8 to 13.3 (95% CI 2.5-50.8). CONCLUSION In thalassaemia, MRI is an alternative means of assessing iron stores, but when it is not available serum ferritin can be used to estimate liver T2*.

Aspirin resistance in children and young adults with splenectomized thalassemia diseases

Aspirin is now recommended for splenectomized thalassemia patients with high platelet counts. However, aspirin resistance defined by arachinodic acid (ACA) induced platelet aggregation ≥20%, has never been reported in this group of patients. In this study, twenty-four splenectomized thalassemia patients (15.7±4.1years), with platelet counts ≥800x10(9)/L, and 21 non-splenectomized severe thalassemia patients (14.3±3.2years), were enrolled. After taking aspirin (2mg/kg/day), seven patients (29.2%) displayed aspirin resistance. Serum thromboxane B2 (TXB2) levels in the aspirin responsive group decreased significantly [52.6(8.8-174.6) vs 4.0(1.6-7.3) mcg/mL, p<0.001], while no change was demonstrated in the aspirin resistant group. Having increased aspirin to 4mg/kg/day, three of the seven aspirin resistant patients responded, while one developed upper GI bleeding from esophageal varices and was withdrawn from the study. For the three remaining patients, their doses were increased to the maximum of 300mg/day, and two of the three responded. Thrombin antithrombin complex and D-dimer levels were significantly decreased after taking aspirin (2mg/kg/day), although D-dimer level was still significantly higher than that in non-splenectomized group. Therefore, aspirin dosage can be adjusted individually to reach maximum effect of platelet inhibition. In addition, aspirin can reduce the levels of coagulation markers.

Lipoprotein(a) and the risk of thromboembolism in Thai children

High lipoprotein(a) [Lp(a)] level was identified as a risk factor of both venous and arterial thromboembolism (TE), especially in Caucasian children. The Lp(a) level is affected by apo(a) gene. The genetic polymorphisms that associated with Lp(a) level are the size of apo(a) gene, pentanucleotide repeat (TTTTA)(n) and +93C/T at promoter region. The increasing size of apo(a) gene, more than 8 pentanucleotide repeats and +93C>T polymorphisms are associated with low level of Lp(a) in African and Caucasian populations. This cross - sectional, case control study, aims to identify the association of Lp(a) level and the risk for TE in Thai children. Forty-nine patients and 116 healthy children were enrolled. Mean ± SD for age of patients and controls were 7.6 ± 4.7 and 11.2 ± 1.7 years, with female:male ratios of 1:1.2 and 1.8:1, respectively. The median Lp(a) levels in patients was 8.2 (0-87.3) mg/dL and 7.9 (0-74.9) mg/dL in controls, which were not statistically different, P=0.65. The frequencies of 8 pentanucleotide repeats and +93C/T were different compared to Caucasian and African populations but similar to Chinese population. However, both polymorphisms did not affect the level of Lp(a).

R147W in PROC Gene Is a Risk Factor of Thromboembolism in Thai Children

The p.R147W mutation, the c.C6152T in exon 7, causing a change in amino acid from arginine to tryptophan of the PROC gene has been reported as a common mutation in Taiwanese populations with venous thromboembolism (VTE). The present study aimed to identify the prevalence of p.R147W in the Thai population and children with TE and the risk of developing TE. Patients aged ≤18 years diagnosed with TE were enrolled. The PROC gene was amplified by polymerase chain reaction using a specific primer in exon 7. The restriction fragment length polymorphism was designed using MwoI restriction enzyme. A total of 184 patients and 690 controls were enrolled. The most common diagnosis of TE was arterial ischemic stroke (AIS), at 100 (54.3%), followed by VTE, at 38 (20.6%), and cerebral venous sinus thrombosis (CVST), at 23 (12.5%). The prevalence of heterozygous and homozygous p.R147W in patients and controls was 9.5% versus 5.8% and 2.7% versus 0.1%, respectively. Heterozygous p.R147W had odds ratios (ORs) of 1.8 (95% confidence interval [CI]: 1.0-3.2, P = .04), 3.2 (95% CI: 1.2-8.2, P = .009), and 4.5 (95% CI: 1.6-12.8, P = .002) of developing overall TE, VTE, and CVST, respectively. Homozygous p.R147W had ORs of 20.2 (95% CI: 2.3-173.7, P < .001), 21.4 (95% CI: 2.2-207.9, P < .001), and 43.3 (95% CI: 3.8-490.6, P < .001) of developing overall TE, AIS, and CVST, respectively. This study suggested that p.R147W is a common mutation and increased risk of TE in Thai children.

Prenatal diagnosis for haemophilia: the Thai experience

Haemophilia is a lifelong X‐linked recessive inherited bleeding disorder. Since the haemophilia management in economically less‐developed countries is inadequately provided, prevention of new cases of haemophilia is essentially required.

High Factor VIII and Von Willebrand Factor Levels Are Not Risk Factors of Cryptogenic Arterial Ischemic Stroke in Thai Children

High factor VIII levels and a risk factor of arterial ischemic stroke is controversial. Levels of factor VIII depend on ethnicity, age, and sex. This report included 24 Thai children with cryptogenic arterial ischemic stroke and 41 controls, with a mean (standard deviation) age of 11.5 (6.3) and 9.0 (4.7), respectively. The study was performed during the post–arterial ischemic stroke events to avoid acute phase reaction of factor VIII and von Willebrand factor. The levels of factor VIII activity and von Willebrand factor antigen in patients were not significantly different compared to controls (119.8 ± 41.3% vs 138.0 ± 48.7%, P = .29 and 92.8 ± 29.8% vs 103.7 ± 39.1%, P = .4, respectively). Therefore, high factor VIII and von Willebrand factor antigen levels were not risk factors of cryptogenic arterial ischemic stroke in Thai children.