De Novo Noninversion Variants Implicated in Sporadic Hemophilia A: A Variant Origin and Timing Study

Sporadic hemophilia A (HA) enables the persistence of HA in the population. F8 gene inversion originates mainly in male germ cells during meiosis. To date, no studies have shown the origin and timing of HA sporadic noninversion variants (NIVs); herein, we assume that HA-sporadic NIVs are generated as a de novo variant. Of the 125 registered families with HA, 22 were eligible for inclusion. We conducted a linkage analysis using F8 gene markers and amplification refractory mutation system-quantitative polymerase chain reaction to confirm the origin of the sporadic NIVs (~0% mutant cells) or the presence of a mosaic variant, which requires further confirmation of the origin in the parent. Nine mothers, four maternal grandmothers, and six maternal grandfathers were confirmed to be the origin of sporadic NIVs, which most likely occurred in the zygote within the first few cell divisions and in single sperm cells, respectively. Three mothers had mosaic variants, which most likely occurred early in postzygotic embryogenesis. All maternal grandparents were free from sporadic NIV. In conclusion, F8 NIVs in sporadic HA were found to be caused primarily by de novo variants. Our studies are essential for understanding the genetic pathogenesis of HA and improving current genetic counseling.

Estimating the impact of improved management of haemophilia a on clinical outcomes and healthcare utilisation and costs

OBJECTIVE

Haemophilia A (HA) is associated with high clinical and healthcare burden. We developed an Excel-based model comparing current practice to improved management in severe HA patients currently managed on demand (OD). Outcomes included short- and long-term bleed events. Expected annual bleeds were estimated based on locally-derived OD annualised bleed rate (ABR), adjusted by relative prophylaxis-related ABRs (published literature). The objective of our study was to explore the impact of improving HA prophylaxis in target countries with limited published data (Algeria, Argentina, Chile, India, Malaysia, Mexico, Taiwan and Thailand). Bleed-related healthcare resource use (HCRU) and costs were estimated as a function of bleed type, with inputs obtained from local expert estimates. Clotting factor concentrates (CFC) consumption related to treatment and prophylaxis was estimated based on locally relevant dosing. CFC costs were not included.

RESULTS

When 20% of OD patients were switched to prophylaxis, projected reduction in bleeds was estimated between 3% (Taiwan) through 14% (Algeria and India); projected reductions in hospitalisations ranged from 3% (Taiwan) through 15% (India). Projected HCRU-related annual cost savings were estimated at USD 0.45 m (Algeria), 0.77 m (Argentina), 0.28 m (Chile), 0.13 m (India), 0.29 m (Malaysia), 2.79 m (Mexico), 0.15 m (Taiwan) and 0.78 m (Thailand). Net change in annual CFC consumption ranged from a 0.05% reduction (Thailand) to an overall 5.4% increase (Algeria). Our model provides a flexible framework to estimate the clinical and cost offsets of improved prophylaxis. Modest increase in CFC consumption may be an acceptable offset for improvements in health and healthcare capacity in resource constrained economies.

Efficacy, safety and cost of emicizumab prophylaxis in haemophilia A patients with inhibitors: A nationwide observational study in Taiwan

INTRODUCTION

Emicizumab mimicking the cofactor function of activated factor VIII (FVIII) restores haemostasis.

METHODS

This nationwide observational study aimed to retrospectively investigate efficacy, safety, and cost in 1 year before and up to 3 years after emicizumab prophylaxis for haemophilia A (HA) patients with FVIII inhibitors.

RESULTS AND DISCUSSION

A total of 39 severe HA patients with a median age of 23.0 years were enrolled. The median historical peak FVIII inhibitor titre was 174.2 BU/mL with an interquartile range of 56.5-578.8 BU/mL. The median annualized bleeding rate reduced from 24 to 0 events in the first year after emicizumab prophylaxis (p < .01) and sustained in the second and third years. The median annualized joint bleeding rate reduced to 0 and maintained up to 3 years (p < .01). Twenty-seven patients (69.2%) had target joints before emicizumab prophylaxis and only seven patients (17.9%) of them had target joints after prophylaxis. Medical costs, including cost of haemostatic therapy, frequency of outpatient department visits, emergency room visits and hospital admission, were significantly reduced after emicizumab prophylaxis (p < .01). FVIII inhibitor titre decreased after emicizumab prophylaxis. Overall, three (7.7%) patients experienced 202 grade 1 drug-related adverse events after emicizumab prophylaxis. No serious adverse events were reported during emicizumab prophylaxis period. The adherence to emicizumab prophylaxis was 100% up to 3 years.

CONCLUSIONS

HA patients with FVIII inhibitors treated with emicizumab prophylaxis resulted in a significant reduction in treated bleeds and associated costs. No new safety events were observed.

Deep vein thrombosis after open hepatectomy or other major upper abdominal surgery in Taiwan: A prospective and cross-sectional study relevant to the issue of pharmacological thromboprophylaxis

BACKGROUD/PURPOSE

Venous thromboembolism, including deep vein thrombosis (DVT) and pulmonary embolism (PE), is an important complication in patients who underwent open hepatic surgery as well as other major upper abdominal surgery. This study aims to investigate the occurrence of postoperative DVT without pharmacological thromboprophylaxis in such cohorts in Taiwan.

METHODS

This is a prospective, cross-sectional cohort study conducted from March 2010 to December 2011. Patients who underwent major upper abdominal surgery, including open hepatectomy, were enrolled. Color duplex compression ultrasonography (CUS) was used to detect DVT. Symptomatic PE was excluded if there were no suggestive respiratory symptoms or sudden death. Relevant clinicopathological and surgical information of each patient was collected and analyzed.

RESULTS

195 patients (118 male and 77 female) were enrolled, with a median age of 63.6 years. The majority (169/195, 88.7%) were treated for active malignancy. Totally 147 patients received open hepatectomy. Only one asymptomatic and distal postoperative DVT event was identified by CUS, which occurred on a 73-year-old female patient who received a left lateral segmental hepatectomy for removing the advanced hepatocellular carcinoma (pathologic stage, T3aN0M0). No cases of symptomatic PE or sudden death were observed. No correlation between DVT and precipitating factor was demonstrated in our cohort.

CONCLUSION

Without pharmacological thromboprophylaxis, a low rate of postoperative DVT among patients undergoing open hepatectomy (0.7%, 1/147) or major upper abdominal surgery (0.5%, 1/195) in Taiwan was reported. A distinctively regional role of pharmacological thromboprophylaxis for hepatic surgery was also suggested by our data.

A large family of hereditary spherocytosis and a rare case of hereditary elliptocytosis with a novel SPTA1 mutation underdiagnosed in Taiwan: A case report and literature review

RATIONALE

Hereditary spherocytosis (HS) has a defect in the vertically connected proteins on the cell membrane of red blood cells (RBC). Hereditary elliptocytosis (HE) has a defect in proteins that connect the cell membrane horizontally. We reported two families of RBC membrane disorders in Taiwanese, one was HS and the other was HE.

PATIENT CONCERNS

Case 1. A 19-year-old male student with chronic jaundice and splenomegaly. His mother, maternal uncle, grandmother, and many members of older generations also had splenomegaly and underwent splenectomy. Case 2. A 40-year-old man has experienced pallor and jaundice since the age of 20 and was found to have splenomegaly, and gall bladder stones in the older age. His younger sister also had pallor and jaundice for a long time.

DIAGNOSES

In case 1, a peripheral blood smear showed 20% spherocytes. Eosin-5-maleimide labeled RBC by flow cytometry showed a result of 30.6 MCF (cutoff value: 45.5 MCF). He was diagnosed with HS. The gene analysis identified a heterozygous mutation with c.166A > G (p.Lys56Glu) in the SLC4A1 gene in this proband, his mother, and maternal uncle. In case 2, more than 40% of ellipsoid RBC present in the peripheral blood smear. He was diagnosed with HE. Genetic analysis of the SPTA1 gene identified a novel heterozygous exon2, c.86A > C, p.Gln29Prol mutation.

INTERVENTIONS

The two patients had compensated anemia, clinical follow-up instead of splenectomy was done.

OUTCOMES

The two patients had normal daily activities and lives.

LESSONS

We reported two Taiwanese families, one was hereditary spherocytosis affected by a heterozygous mutation with c.166A > G (p.Lys56Glu) in SLC4A1, and the other was hereditary elliptocytosis caused by a novel heterozygous SPTA1 gene mutation, c. 86A > C, p.Gln29Prol. These 2 seemingly common hereditary red blood cell membrane protein defects induced by hemolysis are usually underdiagnosed or misdiagnosed.

Congenital factor V deficiency in Taiwan: identification of a novel variant p.Tyr1813 ∗ and two variants specific to East Asians

Congenital coagulation factor V deficiency (FVD) is a rare, autosomal recessive bleeding disorder. We characterized the clinical presentations, laboratory features, and genetic alterations of Taiwanese patients with FVD. From 1983 to 2010, five women, one man, and one boy diagnosed with FVD were enrolled in this study. The factor V coagulant activity was determined using a one-stage prothrombin time-based test. The factor V antigen level was measured in an ELISA. Sanger sequencing was performed for genetic analyses of F5 , the gene responsible for the disease. One novel and de novo F5 genetic variant, p.Tyr1813 ∗ , was identified. Based on the presence of a premature termination codon with a resultant truncated factor V-protein lacking an intact light chain fragment, the variant is pathogenic. In addition, we identified seven variants previously found to cause FVD. Among them, p.Gly420Cys and p.Asp96His were repeatedly detected in five and four patients, respectively. Both variants are found to be specific to the East Asian populations. Various FVD-associated bleeding manifestations were observed, predominantly mucocutaneous bleeding and hypermenorrhea. All patients exhibited very low factor V coagulant activity (<1-2.5 IU/dl, reference range: 60-133 IU/dl). The factor V antigen level was less than 2% in six patients (reference range: 75-157%). The novel F5 genetic variant p.Tyr1813 ∗ and two distinct, East Asians-specific, recurrent variants p.Gly420Cys and p.Asp96His were identified among seven index patients with FVD in Taiwan. Our clinical and laboratory findings support the reported features of FVD.

Origin and timing of de novo variants implicated in type 2 von Willebrand disease

Very few studies have shown the real origin and timing of de novo variants (DNV) implicated in von Willebrand disease (VWD). We investigated four families with type 2 VWD. First, we conducted linkage analysis using single nucleotide variant genotyping to recognize the possible provenance of DNV. Second, we performed amplification refractory mutation system‐quantitative polymerase chain reaction to confirm the real origin of variant (~0% mutant cells) or presence of a genetic mosaic variant (0%–50% mutant cells) in three embryonic germ layer‐derived tissues and sperm cells. Then, three possible timings of DNV were categorized based on the relative likelihood of occurrence according to the number of cell divisions during embryogenesis. Two each with type 2B VWD (proband 1 p.Arg1308Cys, proband 4 p.Arg1306Trp) and type 2A VWD (proband 2 p.Leu1276Arg, proband 3 p.Ser1506Leu) were identified. Variant origins were identified for families 1, 2 and 3 and confirmed to originate from the mother, father and father, respectively. However, the father of family 4 was confirmed to have isolated germline mosaicism with 2.2% mutant sperm cells. Further investigation confirmed the paternal grandfather to be the origin of variant. Thus, we proposed that DNV originating from the two fathers most likely occurred at the single sperm cell, the one originating from the mother occurred at the zygote during the first few cellular divisions; alternatively, in family 4, the DNV most likely occurred at the early postzygotic development in the father. Our findings are essential for understanding genetic pathogenesis and providing accurate genetic counselling.

Characterization of congenital factor XII deficiency in Taiwanese patients: identification of one novel and one common mutation

Background

Factor XII (FXII) deficiency is an interesting condition that causes prolonged activated partial thromboplastin time without bleeding diathesis. FXII may be not important in hemostasis, but still plays roles in thrombosis and inflammation. In order to raise clinical awareness about this condition, we studied patients with severe FXII deficiency and their relatives.

Methods

Consecutive severely FXII deficient patients presenting from 1995 to 2020 were recruited from two medical centers in Taiwan. Index patients and their families were tested for FXII function, antigen and F12 gene. F12 variants were constructed into the pIRES-hrGFP vector and expressed on human embryonic kidney cells (HEK293T). FXII antigen and activity were analyzed.

Results

We found five severely FXII deficient patients, three women and two men, aged 44–71 years. FXII antigen results ranged from undetectable to 43.7%. Three different mutations were identified: c.1681C>A (p.Gly542Ser), c.1561G>A (p.Glu502Lys), and a novel mutation c.1556T>A (p.Leu500Gln). HEK293T cells expressed consistently low FXII activity with all mutations. FXII antigen expression was similar to the wild type in c.1681C>A (p.Gly542Ser), but reduced in c.1556T>A (p.Leu500Gln) and c.1561G>A (p.Glu502Lys).

Conclusions

We report five unrelated patients with severe FXII deficiency, one of whom carried a novel, cross-reacting material negative mutation c.1556T>A (p.Leu500Gln).

Prevalence of non-Alcoholic Fatty Liver Disease and Associated Factors in Patients with Moderate or Severe Hemophilia: A Multicenter-Based Study

Introduction

Liver health is essential for persons with hemophilia (PWH) in order to maintain access to new therapies, such as gene therapy. Non-alcoholic fatty liver disease (NAFLD) is seldom reported in the hemophilia population. The study aimed to investigate the prevalence of NAFLD and associated factors in PWH.

Methods

Data of this cross-sectional study were obtained from a multicenter collaborative registry database.

Results

A total of 163 moderate or severe PWH with a complete data of liver examination were analyzed. There were 77 (47.2%) PWH diagnosed with NAFLD. The multivariate analysis showed that overweight/obesity was associated with NAFLD (OR, 4.31, P < .001). In comparison with hemophilia B patients, hemophilia A patients showed a weaker correlation with NAFLD, (OR, 0.30, P = .009). A total of 17 (25.8%) PWH with NAFLD had an elevated level of alanine transaminase (ALT). Both overweight/obesity and presence of inhibitor to clotting factor were independently associated with elevated ALT in PWH with NAFLD.

Conclusions

The study indicated that a high prevalence of NAFLD existed in the hemophilia population. Overweight/obesity was an independent factor for NAFLD and elevated ALT.

Clinical features and genetic defect in six index patients with congenital fibrinogen disorders: Three novel mutations with one common mutation in Taiwan's population

INTRODUCTION

Congenital fibrinogen disorders (CFDs) are caused by mutations in fibrinogen-encoding genes, FGA, FGB, and FGG, which lead to quantitative or qualitative abnormalities of fibrinogen. Although the diagnosis of CFDs is based on antigenic and functional level of fibrinogen, few genotypes are clearly correlated with phenotype.

METHODS

In this study, we investigated all of the referred patients diagnosed as CFDs in Taiwan's population between 1995 and 2020. Clinical features, laboratory data and genetic defects were analysed. Functional fibrinogen level was determined by the Clauss method. Antigenic fibrinogen was measured by an enzyme-linked immunosorbent assay. Fibrinogen genes were assessed for mutations by polymerase chain reaction and sequencing.

RESULTS

A total of 18 patients from six unrelated families with CFDs were identified. One patient from a consanguineous family was diagnosed as afibrinogenemia type 1A with a novel homozygous frameshift mutation in FGB exon 4. The other five (83.3 %) index patients were all diagnosed as dysfibrinogenemia type 3A caused by two novel and one known mutation. Six (33.3 %) patients from three families had a novel mutation in FGB exon 8. The clinical features and laboratory data were highly variable among these patients with the same mutation.

CONCLUSIONS

Three novel mutations of CFDs causing afibrinogenemia and dysfibrinogenemia were identified. The point mutation in FGB exon 8 is also a common mutation in Taiwan's population. Considerable phenotypic variability among the patients with an identical mutation was observed.

Review article inferior vena cava thrombosis: a case series of patients observed in Taiwan and literature review

Inferior vena cava thrombosis (IVCT) is rare and can be under-recognized. However, the associated complications and mortality may be severe. We report the first case series of IVCT observed in Taiwan with a brief literature review. Eight Taiwanese patients with IVCT between May 2012 and December 2019 were enrolled in this study. Deep venous thrombosis (DVT, 8/8) and pulmonary embolism (5/8) were reported. Various risk factors were identified, including an unretrieved inferior vena cava (IVC) filter, pregnancy, surgery, presence of lupus of anticoagulants, essential thrombocythemia, antithrombin deficiency, and hemoglobin H disease. Of note, four of our patients experienced complete IVC thrombosis with bilateral lower extremity swelling (due to DVT) and abdominal wall superficial venous dilatation, while four other patients presented with partial IVCT and unilateral DVT. The etiology, clinical characteristics, presentations, diagnosis, and treatment of IVCT were reviewed.

First reported case of congenital thrombotic thrombocytopenic purpura in Taiwan with novel mutation of ADAMTS13 gene

Congenital thrombotic thrombocytopenic purpura (cTTP) is a rare disease that is defined as biallelic mutations of ADAMTS13 causing persistent absence of ADAMTS13 activity. The confirmed diagnosis requires a genetic study, and cTTP has never been previously reported in Taiwan. Our patient was a 29-year-old Taiwanese woman who presented with severe hyperbilirubinemia at birth. She had severe thrombocytopenia and hemolytic anemia at the age of 1, and another acute TTP event at the age of 7 triggered by an upper airway infection. Regular plasma replacement was started at age 12 based on a presumptive diagnosis of cTTP. Clinical diagnosis of cTTP, with undetectable ADAMTS13 activity and absence of ADAMTS13 inhibitor, was confirmed at age 27. A genetic study showed a previously reported mutation c.1921G to A, inherited from her father, and a maternally inherited, novel mutation at exon 12, c.1435+1dupG, which results in a splicing site change and frame shift. Reports of cTTP from East Asia, except Japan, are scarce. Some prevalent ADAMTS13 mutations are also race or region specific. With this report, we hope to raise awareness among physicians in Taiwan, promote early, proper diagnosis of cTTP, and reveal the true prevalence of cTTP in the Taiwanese population.

A systematic review evaluating the efficacy and factor consumption of long-acting recombinant factor VIII products for the prophylactic treatment of hemophilia A

AIMS

Long-acting (LA) recombinant FVIII (rFVIII) products with extended dosing intervals have been developed for the treatment of hemophilia A; however, no direct head-to-head trial has been conducted to compare the efficacy of these products.

MATERIALS AND METHODS

A systematic literature search was conducted to identify published Phase III clinical trials of prophylactic LA rFVIII treatment in previously treated patients aged ≥12 years, with moderate-to-severe hemophilia A (endogenous FVIII levels ≤2%). Studies that did not meet these criteria, or did not report the included outcomes, were excluded. Bleeding rates and consumption were extracted and summarized; only data for the dosing frequencies indicated in the US product labels (which are similar to those indicated in the European Medicines Agency labels) were included.

RESULTS

Five articles met the inclusion criteria; these studies only included patients with severe hemophilia A. Treatment length, reported outcomes and dose (range: 20-65 IU/kg) varied between studies. Median annualized bleeding rate (ABR) (IQR) reported in the relevant studies was 1.14 (0.00-4.30), rVIII-SingleChain 2 or 3 times weekly; 1.6 (0.0-4.7), rFVIIIFc 2 times weekly followed by every 3-5 days; 1.9 (0.0-5.8), BAX855 2 times weekly; 1.18 (0.00-4.25), N8-GP every 4 days; 1.9 (0.0-5.2) and 4.1 (2.0-10.6), BAY 94-9027 2 times weekly for the cohort who experienced >1 or <1 bleed in the study run-in phase, respectively. Median spontaneous ABR was 0.0 across studies reporting relevant data. Reported consumption was comparable among all LA products.

LIMITATIONS

The primary limitation of this systematic review was the variation in study design and not all studies reported all desired outcomes, which limited the quantity of data available.

CONCLUSIONS

This systematic review identified pivotal trial data for LA rFVIII products. Real-world evidence is needed to understand how these products perform in clinical practice.

A family with an MYH9-related disorder with different phenotypes masquerading as immune thrombocytopaenia: an underreported disorder in Taiwan

A 66-year-old woman had experienced abnormal bleeding since the age of 7. Thrombocytopenia was not detected until she was 48, and immune thrombocytopenia was diagnosed at age 66. She also reported experiencing hearing disturbance since the age of 30 and acute renal failure since the age of 61 but reported no visual disturbance. Her younger son, who was 40 years old, also experienced abnormal bleeding since the age of 6, but immune thrombocytopenia was diagnosed as late as age 35. He had no other associated disorders. Laboratory examinations of both mother and son revealed a low platelet count (8000 and 29,000 µL, respectively), giant platelets and Döhle body-like granulocyte inclusion bodies. The mother had a high creatinine level (15.4 mg/dL) and normal liver enzyme levels. MYH9 genetic analysis identified a heterozygous mutation, c.101T>A, p.Val34Glu at exon 2 in both patients. These clinical and laboratory findings were consistent with a diagnosis of an MYH9-related disorder with different phenotypes observed in the same family. MYH9-related disorders were recognised in 2003, but were often misdiagnosed as immune thrombocytopenia, and hence, they have rarely been reported in Taiwan.

Characterization of hereditary factor XI deficiency in Taiwanese patients: identification of three novel and two common mutations

Hereditary coagulation factor XI (FXI) deficiency is a rare bleeding disorder, but information on FXI deficiency in Taiwanese patients remains scarce. We evaluated clinical and genetic features of severe FXI deficiency patients in Taiwan. We collected clinical information and performed coagulation laboratory tests and genetic studies in ten unrelated Taiwanese families with severe FXI deficiency. FXI coagulation activity was assayed using a one-stage method. FXI antigen was determined using enzyme-linked immunosorbent assay. Underlying genetic mutations were evaluated using direct sequencing methods. Ten unrelated Taiwanese patients with hereditary FXI deficiency and variable bleeding tendencies were analyzed. Half of the patients were male. The most common bleeding manifestations were easy bruising (40%), bleeding after dental procedures (40%), and postoperative bleeding (33%). Two patients (20%) were asymptomatic. No correlation was found between bleeding manifestations and baseline FXI levels. Three novel mutations were identified: c.1322delT p.Lys442Cysfs*8, c.599G > C p.Cys200Ser, and IVS4 c.325 + 2del124. Two common mutations, c.1107C > T p.Tyr369* (40%) and c.841C > T p.Gln281* (30%), were also found. No correlation existed between bleeding and FXI activity, highlighting the difficulty in predicting FXI deficiency-related bleeding. Three novel FXI genetic mutations and two common mutations were identified, contributing to the known spectrum of FXI deficiency-related mutations.

Segmental uniparental disomy as a rare cause of congenital severe factor XIII deficiency in a girl with only one heterozygous carrier parent

Uniparental disomy (UPD) refers to a situation when a person inherits both homologs of a region or complete part of a chromosome from only one parent. Here, we present an unusual case of UPD in congenital severe factor (F) XIII deficiency. A 6-year-old girl experienced cephalhematoma and umbilical bleeding after birth and easy bruising, and postextraction bleeding since early infancy. FXIII activity was 0% [mother 53.7% and father 132.5% (normal 70-140%)] and the FXIII antigen level was 2.5% [mother 38.9% and father 151% (normal 75-155%)]. The washed platelet FXIII activity was 0.1% in the patient (normal 64-144%), suggesting a deficiency of FXIII-A subunit. The FXIII-A subunit genetic analysis detected a homozygous p.Arg382Ser mutation. A similar heterozygous mutation was detected in the mother but surprisingly, not in the father. Kinship was confirmed by a paternity test. To confirm the possibility of UPD, a test using four markers in the vicinity of the F13A1 gene revealed that she inherited duplicate mutations from a heterozygous mutation in her mother, presenting a unique case of unusual maternal segmental UPD in otherwise unexplained congenital (homozygous) severe FXIII deficiency. UPD as a rare cause of autosomal recessive bleeding disorder when only one parent is affected is critical for genetic counseling.

Analysis of Human Platelet Glycoprotein llb-llla by Fluorescein Isothiocyanate-Conjugated Disintegrins with Flow Cytometry

Disintegrins are a group of snake venom peptides which inhibit human platelet aggregation by acting as glycoprotein Ilb-IIIa (GPIIb-Ilia) antagonists. They are cysteine-rich, Arg-Gly-Asp (RGD)-containing peptides, and bind to GPIIb-Ilia complex on platelet membrane with a very high affinity (Kd, 10−7 ∼ 10−8 M). In this study, we analyzed GPIIb-Ilia complex on platelet membrane by flow cytometry using fluorescein isothiocyanate (FITC)-conjugated disintegrins as probes. Of these FITC-conjugated disintegrins, FITC-Rhodostomin is the most sensitive probe because Rhodostomin was conjugated with more FITC molecules than Trigramin and Halysin were. The binding fluorescence intensity of FITC-Trigramin (FITC-Tg), FITC-Halysin (FITC-Hy) and FITC-Rhodostomin (FITC-Rn) was measured in both resting and ADP-activated platelets of diluted human platelet-rich plasma. The binding fluorescence of FITC-disintegrins was abolished by EDTA and 7E3, a monoclonal antibody against GPIIb-Ilia. ADP markedly increased the fluorescence intensity of FITC-Tg and FITC-Hy bound on platelets especially when lower doses of these probes were used, whereas it had little effect on that of FITC-Rn. Therefore, FITC-Tg and FITC-Hy can be used for the detection of the activated platelets as noted by a higher ratio of fluorescence intensity (approx. 2-4) between ADP-activated and resting platelets as compared with that (approx. 1-1.3) in the case of FITC-Rn as the probe. The platelets from three patients with Glanzmann’s thrombasthenia were probed with FITC-disintegrins. As a result these three patients could be classified as type I thrombasthenia based on the extremely low level of GPIIb-Ilia detected by this method (<5% of normal value).

Genetic Basis and Carrier Detection of Hemophilia B of Chinese Origin

We have characterized the genetic defects of 17 hemophilia B patients of Chinese origin by means of the polymerase chain reaction (PCR) and direct sequencing. The single-strand conformation polymorphism (SSCP) was used as an initial screening method to analyze the entire coding region and the flanking introns of each individual’s factor IX gene. The abnormal exons were subsequently amplified and the nucleotide sequence determined. Of the 17 patients studied, 16 had single point mutations and one had a gross gene deletion of exons VII and VIII of factor IX. Among these 16 factor IX variants with point mutations 13 were missense and two were nonsense mutations. The remaining one had a nucleotide deleted, resulting in frame shifting at amino acid residue 97. A total of ten novel mutations, including the one with gross gene deletion, are reported in this study which have not been described previously. Five of the remaining seven variants were missense mutations with novel amino acids substituted for residues 127, 132, 180, 207, and 215, respectively. Mutations containing different amino acid residues at those positions have been reported. The last two are variants that have already been described to contain mutations at amino acid residues 333 and 365, respectively. To evaluate the efficiency of SSCP analysis in assessing the mutated exons and to further confirm our results we sequenced the entire exons of all 17 factor IX genes. The mutations detected by SSCP method were indeed the only mutation identified in each factor IX variant. The SSCP analysis and direct sequencing have also allowed us to circumvent the difficulties of carrier determination for Chinese by direct detection of the abnormal factor IX alleles inherited by the females.

Hemophilia B with Mutations at Glycine-48 of Factor IX Exhibited Delayed Activation by the Factor VIIa-tissue Factor Complex

Gly-48 is in the conserved DGDQC sequence (residues 47-51 of human factor IX) of the first EGF (EGF-1)-like domain of factor IX. The importance of the Gly-48 is manifested by two hemophilia B patients; factor IXTainan and factor IX>Malmö27, with Gly-48 replaced by arginine (designated IXG48R) and valine (IXG48V), respectively. Both patients were CRM+ exhibiting mild hemophilic episodes with 25% (former) and 19% (latter) normal clotting activities. We characterize both factor IX variants to show the roles of Gly-48 and the conservation of the DGDQC sequence in factor IX. Purified plasma and recombinant factor IX variants exhibited approximately 26%–27% normal factor IX’s clotting activities with G48R or G48V mutation. Both variants depicted normal quenching of the intrinsic fluorescence by increasing concentrations of calcium ions and Tb3+, indicating that arginine and valine substitution for Gly-48 did not perturb the calcium site in the EGF-1 domain. Activation of both mutants by factor XIa appeared normal. The reduced clotting activity of factors IXG48R and IXG48V was attributed to the failure of both mutants to cleavage factor X; in the presence of only phospholipids and calcium ions, both mutants showed a 4∼7-fold elevation in K m, and by adding factor VIIIa to the system, although factor VIIIa potentiated the activation of factor X by the mutants factor IXaG48R and factor IXaG48V, a 2∼3-fold decrease in the catalytic function was observed with the mutant factor IXa’s, despite that they bound factor VIIIa on the phospholipid vesicles with only slightly reduced affinity when compared to wild-type factor IXa. The apparent K d for factor VIIIa binding was 0.83 nM for normal factor IXa, 1.74 nM for IXaG48R and 1.4 nM for IXaG48V. Strikingly, when interaction with the factor VIIa-TF complex was examined, both mutations were barely activated by the VIIa-TF complex and they also showed abnormal interaction with VIIa-TF in bovine thromboplastinbased PT assays. Taken together, our results suggest that mutations at Gly-48 altered the interaction of factor IX with its extrinsic pathway activator (VIIa-TF complex), its macromolecular substrate (factor X), and its cofactor (factor VIIIa).

Factor V Arg306 → Gly Mutation Is not Associated with Activated Protein C Resistance and Is rare in Taiwanese Chinese

Polymerase chain reaction amplification followed by BstOI enzyme digestion and DNA sequencing was employed to detect the mutation of factor V gene. The subjects consisted of 105 venous thrombophilic patients and 183 healthy controls. Only one patient was found to have factor V Arg306 → Gly mutation, his elder son also had an identical mutation. None of the healthy subjects studied had Arg306 → Thr mutation. The rare event of factor V Arg306 → Gly mutation in patients and controls suggest that this mutation is not associated with increased risk of venous thrombosis. Conventional, modified and extended activated protein C (APC) resistance assays in this patient and his family members clearly showed that factor V Arg306 → Gly mutation is not associated with APC resistance (APC sensitivity ratio <2). In conclusion, factor V Arg306 → Gly mutation is rare in Taiwanese Chinese and not associated with APC resistance, it is possibly not a risk factor for venous thrombophilic thrombosis.

Characterisation of factor IX with a glycine-to-valine missense mutation at residue 190 in a patient with severe haemophilia B

A patient with severe haemophilia B with a glycine-to-valine missense mutation at residue 190 (c25, chymotrypsin numbering) in factor IX (FIX; FIX-G190V or FIX-FuChou) had <1% of normal FIX clotting activity and 36% of normal FIX antigen levels (cross-reacting material-reduced, CRMr). Residue 190 in the C-terminal protease domain of human FIX is highly conserved in mammalian species and the serine protease family, suggesting that it has an indispensable role in protein function. To explore the pathological mechanism by which this mutation contributes to dysfunction of the FIX molecule, we functionally characterised FIX-G190V in vitro and in vivo. Liver-specific FIX-G190V gene expression following hydrodynamic plasmid delivery into haemophilia B mice revealed a 5.7-fold reduction in specific clotting activity compared with FIX-WT (wild type) and a two-fold decrease in plasma FIX-G190V concentration. Pulse-chase analysis demonstrated that FIX-G190V was secreted at a significantly slower rate than was FIX-WT. Purified FIX-G190V and FIX-WT displayed normal calcium-dependent conformational changes as shown by intrinsic fluorescence quenching. The in vivo half-lives of FIX-G190V and FIX-WT were indistinguishable. FIX-G190V was, however, more readily degraded than FIX-WT, especially after being activated by the active form of FXI. The vulnerable sites were mapped to the peptide bonds at Arg116-Leu117, Lys265-Tyr266, Arg327-Val328, and Arg338-Ser339, which are in the exposed loops of the FIX molecule. Also, failure of FXIa-activated FIX-G190V to bind p-aminobenzamidine indicated an abnormal conformation of the active-site pocket. Thus, the mutation at residue 190 of FIX may result in protein misfolding that affects secretion, clotting function, and hydrolysis.

Low-molecular-weight-heparin can benefit women with recurrent pregnancy loss and sole protein S deficiency: a historical control cohort study from Taiwan

BACKGROUND

Heritable thrombophilias are assumed important etiologies for recurrent pregnancy loss. Unlike in the Caucasian populations, protein S and protein C deficiencies, instead of Factor V Lieden and Prothrombin mutations, are relatively common in the Han Chinese population. In this study we aimed to investigate the therapeutic effect of low molecular weight heparin upon women with recurrent pregnancy loss and documented protein S deficiency.

METHODS

During 2011-2016, 68 women with recurrent pregnancy loss (RPL) and protein S deficiency (both the free antigen and function of protein S were reduced) were initially enrolled. All the women must have experienced at least three recurrent miscarriages. After excluding those carrying balanced translocation, medical condition such as diabetes mellitus, chronic hypertension, and autoimmune disorders (including systemic lupus erythematosus and anti-phospholipid syndrome), coexisting thrombophilias other than persistent protein S deficiency (including transient low protein S level, protein C deficiency, and antithrombin III), only 51 women with RPL and sole protein S deficiency were enrolled. Initially they were prescribed low dose Aspirin (ASA: 100 mg/day) and unfortunately there were still 39 women ended up again with early pregnancy loss (12 livebirths were achieved though). Low-molecular-weight-heparin (LMWH) was given for the 39 women in a dose of 1 mg/Kg every 12 h from the day when the next clinical pregnancy was confirmed to the timing at least 24 h before delivery. The perinatal outcomes were assessed.

RESULTS

Of 50 treatment subjects performed for the 39 women (i.e. 11 women enrolled twice for two pregnancies), 46 singletons and one twin achieved livebirths. The successful live-birth rate in the whole series was 94 % (47/50). Nineteen livebirths delivered vaginally whereas 28 delivered by cesarean section. The cesarean delivery rate is thus 59.57 %. Emergent deliveries occurred in 3 but no postpartum hemorrhage had been noted.

CONCLUSIONS

Our pilot study in Taiwan, an East Asian population, indicated anti-coagulation therapy is of benefit to women with recurrent pregnancy loss who had documented sole protein S deficiency.

TRIAL REGISTRATION

ISRCTN64574169. Retrospectively registered 29 Jun 2016.

Characteristics of Taiwanese patients of PNH in the international PNH registry

Background

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare and acquired hematopoietic stem cell disease, with florid clinical presentations. Although this disease has been characterized in the western countries, its clinical and laboratory features in Taiwan have not yet been reported.

Results

As a part of an international prospective, non-interventional, observational registration trial of PNH, we have analyzed 63 patients recruited between 2009 and 2015 in Taiwan, with comparison to the 3857 patients in the rest of the world (ROW). The median age of diagnosis of our patients is 46 (range 9–84), without sex preponderance. While most of the clinical and laboratory presentations of our patients are similar to the ROW, ours have higher lactate dehydrogenase levels, lower hemoglobin, and higher frequencies of symptoms including shortness of breath and erectile dysfunction at the time of diagnosis. The incidence of thromboembolism was not statistically different between ours and the ROW (6.7 % vs 13.5 %, P = 0.178). The patients in Taiwan were treated more frequently with corticosteroid (53.2 % vs 32 %, P < 0.001), but less frequently with cyclosporine/anti-thymocyte globulin and heparin/warfarin, both P < 0.001).

Conclusions

This is the first systematic review on the Taiwanese PNH patients. Our analysis would provide key information about our PNH patients and would help understanding the basic characteristics of this rare disease in Taiwan.

Trial registration

This trial has been registered to ClinicalTrails.gov NCT01374360.

De novo mutation and somatic mosaicism of gene mutation in type 2A, 2B and 2M VWD

Background

Von Willebrand disease (VWD) is not uncommon in Taiwan. In type 2 or type 3 VWD hemorrhagic symptoms are severer and laboratory data relatively more distinctive. De novo mutation and somatic mosaicism of type 2 VWD gene were rarely reported. Therefore clinical, laboratory and genetic studies of only type 2A, 2B and 2M VWD will be presented and issues of de novo mutation and somatic mosaicism will be explored.

Methods

Fifty-four patients belonging to 23 unrelated families from all around the country in whom type 2 VWD exclusive of type 2N has been diagnosed not only by clinical and routine laboratory studies but also by genetic confirmation during 1990–2015 were investigated. A novel technique named amplification refractory mutation system-quantitative polymerase chain reaction (ARMS-qPCR) was used to confirm the presence of somatic mosaicism. Informed consent was obtained for study.

Results

De novo mutation was identified in 4 families among 15 families (26.7 %) in whom family members including parents were available for examination. All their parents were free from bleeding symptoms and had no similar mutation as their respective affected daughter.

An interesting example of somatic mosaicism of VWF gene mutation was found in a large family with type 2A VWD. The father carrying a mutated VWF gene, p.Arg1597Trp, transmitted this mutation to his 3 daughters, 1 son, 3 granddaughters and 2 grandsons. However, the father had normal laboratory findings and experienced no abnormal bleeding, while his offspring who inherited the mutation showed abnormal laboratory findings compatible with type 2A VWD and had history of abnormal bleedings. ARMS-qPCR revealed that the father had only 25.5 % mutant in his blood cells and 31.1 % mutant in his oral mucosal cells, while all his offspring had about 49 % mutant in their blood cells.

Conclusion

De novo mutation of type 2 VWD gene was identified in 4 out of 15 families (26.7 %) examined. Since only one child was affected in each family, germline mosaicism was not likely. A somatic mosaicism of type 2A VWD gene was documented in a big family by a newly in-house developed technique ARMS-qPCR.

Preimplantation genetic diagnosis of hemophilia A

Preimplantation genetic diagnosis (PGD) is a powerful tool to tackle the transmission of monogenic inherited disorders in families carrying the diseases from generation to generation. It currently remains a challenging task, despite PGD having been developed over 25 years ago. The major difficulty is it does not have an easy and general formula for all mutations. Different gene locus needs individualized, customized design to make the diagnosis accurate enough to be applied on PGD, in which the quantity of DNA is scanty, whereas timely laboratory diagnosis is mandatory if fresh embryo transfer is desired occasionally. Indicators for outcome assessment of a successful PGD program include the successful diagnosis rate on blastomeres (Day 3 cleavage-stage embryo biopsy) or trophectoderm cells (Day 5/6 blastocyst biopsy), the implantation rate per embryo transferred, and the livebirth rate per oocyte retrieval cycle. Hemophilia A (HA) is an X-linked recessive bleeding disorder caused by various types of pathological defects in the factor VIII gene (F8). The mutation spectrum of the F8 is complex, according to our previous report, including large segmental intra-gene inversions, large segmental deletions spanning a few exons, point mutations, and total deletion caused by chromosomal structural rearrangements. In this review, the molecular methodologies used to tackle different mutants of the F8 in the PGD of HA are to be explained, and the experiences of successful use of amplification refractory mutation system-quantitative polymerase chain reaction (ARMS-qPCR) and linkage analysis for PGD of HA in our laboratory are also provided.

Asp68His mutation in the A1 domain of human factor V causes impaired secretion and ineffective translocation

Congenital factor V (FV) deficiency is a rare inherited disorder. We determined the mechanism of a missense mutation, Asp68His, in the A1 domain of the FV protein, is associated with severe FV deficiency. We characterized the mutant FV-Asp68His protein using in vitro expression studies by using specific secretion and degradation pathway inhibitors and analysed the intracellular translocation of the mutant protein by immunofluorescence staining. The Asp68His mutation caused very low levels of FV protein in the conditioned media, with normal specific FV activity. Similar mRNA degradation rates between FV-wild-type (wt) and FV-Asp68His mRNA showed that the Asp68His mutation does not affect FV expression at the transcriptional level. A specific secretion pathway inhibitor, brefeldin A, was used to demonstrate that the lower efficiency of transport to the outside of the cell for FV-Asp68His mutant protein compared with that of the FV-wt protein. Furthermore, we showed that the Asp68His mutation resulted in increased intracellular degradation through a MG132-mediated proteasomal degradation pathway. In the transfected cell lysates, FV-wt protein had multiple posttranslational modified forms, but the FV-Asp68His protein was not completely glycosylated. We further observed that the FV-Asp68His protein was retrieved in the endoplasmic reticulum only and did not undergo transport to the Golgi apparatus, leading to impaired secretion. These results strongly suggest that the Asp68His mutation may result in intracellular defective trafficking and enhanced degradation, and impaired secretion of FV protein.

Functional characterization of a novel missense mutation, His147Arg, in A1 domain of FV protein causing type II deficiency

INTRODUCTION

Congenital factor V (FV) deficiency is a rare inherited disorder. Three compound heterozygous missense mutations, Asp68His, His147Arg, and Arg2074Cys, were observed in a Taiwanese patient with moderately severe FV deficiency.

METHOD

The novel His147Arg mutation in the A1 domain was investigated by protein modeling, followed by in vitro expression studies in COS-1 cells, to elucidate the molecular pathology associated with FV deficiency.

RESULTS

The His147Arg mutation was associated with normal antigen levels, both in cell lysates and conditioned media, whereas FV activity was significantly reduced to 63.5 ± 17.0%. These observations correspond to a type II FV deficiency mutation. Protein modeling by short-duration molecular dynamics (MD) simulation showed that the His147Arg mutation was associated with a conformational change, which could disrupt the stability of FVa by interfering with His1817 coordination of the copper ion. In functional activation assays, the His147Arg mutation did not affect FV protein activation by thrombin; however, reduced cofactor activity of the FVa protein, due to an increased rate of dissociation of heavy and light chains, was observed.

CONCLUSION

Our results show that the His147Arg mutation in the A1 domain of FV does not impair synthesis or procoagulant activity. Instead, the His147Arg mutation appears to disrupt the stability of FVa, providing a potential explanation for the functional deficiency.

Abstract P5-14-07: Comparison of infectious complications between breast conserving therapy with catheter-based accelerated partial irradiation and whole breast irradiation

Standard treatment after breast conserving surgery (BCS) has been whole breast irradiation (WBI), however, accelerated partial breast irradiation (APBI) has recently been shown to be an alternative in a select group of patients. APBI has been associated with early postoperative as well as delayed infections. In the current study, we compared rates of infectious complications between patients treated with catheter-based APBI and WBI.

Patients were identified from a single-institution prospective registry from 2009 to 2011. Selection criteria included patients who underwent BCT with either single-entry APBI or WBI and fulfilled criteria for ABPI including ≥50 years, tumor size ≤ 3cm, pN0, and no lympho-vascular invasion. Data regarding treatment, patient comorbidities, and outcomes were obtained. Infectious complications were assessed from the date of APBI catheter insertion or from the date of surgery to start of WBI. Infectious complications were classified as early (≤ 30 days) or delayed (&gt; 30 days). Fisher's exact test was used to compare the rate of infection between APBI and WBI.

91 patients were treated with single-entry catheter-based APBI and 267 patients were treated with WBI. Median follow-up time was 76.2 weeks for APBI patients and 115 weeks for WBI patients. Re-excision was required in 20 patients (21.7%) who underwent APBI and in 51 patients (19.1%) who underwent WBI. Overall, infection occurred in 13 patients (14.1%) who underwent APBI versus 39 patients (14.6%) who underwent WBI. In the APBI group, three (3.3%) patients had infection within 30 days and 10 (10.9%) had infection more than 30 days after catheter insertion. 24 (9.0%) patients had infections within 30 days after surgery and 15 (5.6%) patients occurred more than 30 days after surgery in the WBI group. Patients began WBI within an average of 84 days after surgery. In the APBI group, 4 patients required hospital admission, 5 patients had percutaneous aspiration, and one needed incision and drainage. 8 patients were managed with outpatient oral antibiotics. In the WBI group, 5 patients required hospital admission, 13 patients had percutaneous aspiration, and 30 patients were managed with outpatient oral antibiotics. Diabetes, smoking, and BMI &gt;25 were factors commonly associated with infectious complications in both APBI and WBI but not statistically significant (P = 0.6, 0.09, 0.1. respectively).

In contrast to other studies showing that patients treated with catheter-based APBI have higher rates of infection than patients treated with WBI, our study found no statistically significant difference in infection rates between the two groups. A majority of infections following APBI or WBI can be medically managed as an outpatient basis.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-14-07.

Body size and the risk of biliary tract cancer: a population-based study in China

Though obesity is an established risk factor for gall bladder cancer, its role in cancers of the extrahepatic bile ducts and ampulla of Vater is less clear, as also is the role of abdominal obesity. In a population-based case–control study of biliary tract cancer in Shanghai, China, odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for biliary tract cancer in relation to anthropometric measures, including body mass index (BMI) at various ages and waist-to-hip ratio (WHR), adjusting for age, sex, and education. The study included 627 patients with biliary tract cancer (368 gall bladder, 191 bile duct, 68 ampulla of Vater) and 959 healthy subjects randomly selected from the population. A higher BMI at all ages, including early adulthood (ages 20–29 years), and a greater WHR were associated with an increased risk of gall bladder cancer. A high usual adult BMI (⩾25) was associated with a 1.6-fold risk of gall bladder cancer (95% CI 1.2–2.1, P for trend <0.001). Among subjects without gallstones, BMI was also positively associated with gall bladder cancer risk. Regardless of BMI levels, increasing WHR was associated with an excess risk of gall bladder cancer risk, with those having a high BMI (⩾25) and a high WHR (>0.90) having the highest risk of gall bladder cancer (OR=12.6, 95% CI 4.8–33.2), relative to those with a low BMI and WHR. We found no clear risk patterns for cancers of the bile duct and ampulla of Vater. These results suggest that both overall and abdominal obesity, including obesity in early adulthood, are associated with an increased risk of gall bladder cancer. The increasing prevalence of obesity and cholesterol stones in Shanghai seems at least partly responsible for the rising incidence of gall bladder cancer in Shanghai.

Hyperhomocysteinemia, deep vein thrombosis and vitamin B12 deficiency in a metformin-treated diabetic patient

Vitamin B12 deficiency may be induced by long-term use of metformin, which may in turn lead to hyperhomocysteinemia. Thus, hyperhomocysteinemia may increase the risk of vascular thrombosis in diabetic patients, when metformin is used and a homozygous methylenetetrahydrofolate reductase (MTHFR) C677T mutation is present. We report a 65-year-old Taiwanese diabetic woman who was treated with metformin for 6 years and who had suffered from swelling of the left lower extremity for 3 months. Ascending venography confirmed the diagnosis of proximal deep vein thrombosis, while hyperhomocysteinemia, megaloblastic anemia caused by vitamin B12 deficiency, and a homozygous C677T mutation of the MTHFR gene were also found. She had no identifiable venous thrombotic risk factors other than hyperhomocysteinemia, which seemed to be caused by both MTHFR C677T homozygous mutation and vitamin B12 deficiency. With the substitution of insulin injection for metformin, short-term supplement of vitamin B12, and anticoagulant therapy for the deep vein thrombosis, her anemia and hyperhomocysteinemia recovered rapidly. The deep vein thrombosis also responded well. Our findings highly suggested the role of metformin in causing vitamin B12 deficiency, which may serve as an additional risk factor for venous thrombosis in diabetic patients. Our report also highlights the need to check vitamin B12 levels during metformin treatment.

Epidemiology of multiple myeloma in Taiwan

BACKGROUND

The incidence of multiple myeloma (MM) is lower in Asia than in western countries. However, no data are available on descriptive epidemiology of MM in Chinese.

METHODS

From 1979 to 2003, 3602 MM patients were registered in the Taiwan National Cancer Registry. The annual incidence and mortality were calculated and age-standardized to the world standard population in the year 2000. Age-period-cohort effects on incidence were analyzed. The salient clinical data of 526 MM patients in a single institute were also investigated.

RESULTS

From 1979 to 2003, the average age-adjusted incidence per 100,000 population was 0.75. The incidence increased with age to a peak of 5.2 in those aged 75-79 years. In addition to age, remarkable period and birth cohort effects were found to contribute to increased incidence of MM. The age-adjusted mortality also increased, which accounted for an average of 0.59 per 100,000 deaths; however, the fatality rate was steady at 80%. Clinical and laboratory characteristics and treatment outcomes of the 526 MM patients were similar to those reported elsewhere. Remarkably, extramedullary myeloma (extra-MM) at diagnosis was more common in patients younger than 55 years of age than in others (43% vs 13%, P < .001).

CONCLUSIONS

Incidence of MM in Taiwan has dramatically increased in recent years and is associated with a birth-cohort effect. There are no apparent differences in treatment outcome between MM patients in Taiwan and in other countries. However, prevalence of extra-MM is higher in patients younger than 55 years of age.

Pharmacokinetic Study of Recombinant Human Factor IX in Previously Treated Patients with Hemophilia B in Taiwan

BACKGROUND/PURPOSE

The pharmacokinetic (PK) study of recombinant human factor IX (rFIX) has been done in patients with hemophilia B in areas other than Taiwan. However, wide patient-related variability in recovery is noted and there is no PK study of rFIX in Taiwanese patients with hemophilia B. The purpose of this study is to evaluate the PKs of the rFIX in Taiwanese patients with hemophilia B.

METHODS

A PK study of rFIX was performed in 10 previously treated Taiwanese patients with hemophilia B. Nine of them had severe hemophilia B and the other one had moderately severe hemophilia B. The mean age of our patients was 24.7 +/- 8.6 years (mean +/- SD) with a range of 15.5-47.0 years.

RESULTS

The infusion of 75 IU/kg of rFIX in our patients resulted in a mean FIX activity increase of 1.08 +/- 0.27 IU/dL per IU/kg with a range of 0.3-1.49 IU/dL per IU/kg, and a mean in vivo recovery of 44.0 +/- 9.5% with a range of 31.4-60.4%. The mean elimination half-life was 24.4 +/- 6.4 hours with a range of 14.1-35.3 hours. The mean values of area under the curve, total body clearance, volume of distribution at steady state were 1363 +/- 166 IU x hour/dL, 4.84 +/- 1.03 mL/hour/kg, and 144.3 +/- 41.8 mL/kg, respectively. In addition, rFIX was well tolerated in our patients. Only two patients experienced mild treatment-related adverse events, including fever and feeling sleepy, respectively. Both of them resolved spontaneously without any sequences, and there was no thrombosis formation or inhibitor development in the following 6 months after rFIX infusion.

CONCLUSION

The results of PK study of rFIX in our previously treated Taiwanese patients with hemophilia B are comparable to the reported results from other related studies conducted in different geographical areas.

Clinical implications of SOCS1 methylation in myelodysplastic syndrome

The suppressor of cytokine signalling-1 (SOCS1) protein is a tumour suppressor. Hypermethylation of SOCS1 gene, resulting in transcriptional silencing, is suggested to play an important role in cancer development. We sought to characterise SOCS1 methylation in primary myelodysplastic syndrome (MDS) and clarify its clinical implications. The methylation status of SOCS1 was analysed by methylation-specific polymerase chain reaction in 114 patients with primary MDS and serial studies were performed in 29 of them. SOCS1 methylation occurred in 54 patients (47.4%), and was more frequent in patients with high-risk MDS than in those with low-risk (52.6% vs. 25.8%, P = 0.011). SOCS1 methylation was closely associated with NRAS mutation (P = 0.010) and inversely associated with good-risk karyotype (P = 0.021). With a median follow-up of 17 months (range: 1-231 months), two patients acquired SOCS1 methylation during disease progression. In two patients, SOCS1 methylation present at diagnosis, disappeared after haematopoietic stem cell transplantation. Patients with SOCS1 methylation had a higher cumulative risk of leukaemic transformation than those without (55.8% vs. 27.7% at 3 years, P = 0.004). This difference remained significant within the subgroup of patients with high-risk MDS (67.3% vs. 45.1% at 3 years, P = 0.045). This is the first report to demonstrate the clinical relevance of SOCS1 methylation in MDS. It may play an important role in the pathogenesis of MDS, especially among patients with high-risk subtypes.

Trends and antimicrobial resistance of pathogens causing bloodstream infections among febrile neutropenic adults with hematological malignancy

BACKGROUND AND PURPOSE

The microbiological spectrum in cancer patients with febrile neutropenia has changed over the past several decades in western countries. The growing incidence of antimicrobial resistance is an inevitable consequence of the widespread use of antibiotics in medical settings. The aim of this study was to clarify the trends and antimicrobial resistance among pathogens causing bloodstream infections in febrile neutropenic adults with hematological malignancies.

METHODS

The characteristics of pathogens causing bloodstream infection isolated from patients with febrile neutropenia who were treated at National Taiwan University Hospital from 1996 to 2001 were reviewed. A total of 1174 pathogens were isolated from 3093 admissions to a hematological ward during this period. Among them, 738 isolates were recovered from patients with febrile neutropenia.

RESULTS

The majority (93%) of these neutropenic febrile patients had underlying acute leukemia or lymphoma. Gram-negative bacteria accounted for 57% of isolated pathogens, followed by Gram-positive bacteria (32%), fungi (7%), and anaerobes (3%). In decreasing frequency, Escherichia coli (13%), Klebsiella pneumoniae (12%), Enterobacter cloacae (7%), Pseudomonas aeruginosa (6%), and Acinetobacter baumannii (5%) were the predominant Gram-negative bacteria, while coagulase-negative staphylococci (13%), viridans group streptococci (4%), and Staphylococcus aureus (4%) were the major Gram-positive pathogens. Two-thirds (20/30) of S. aureus isolates were resistant to oxacillin. No vancomycin-resistant enterococci were isolated. Resistance to cefotaxime was found in 63% of E. cloacae, 13% of K. pneumoniae and 10% of E. coli. Overall, 33% of E. coli and 13% of K. pneumoniae were resistant to ciprofloxacin.

CONCLUSIONS

This study indicates that the microbiological spectrum of microorganisms causing bloodstream infections in neutropenic febrile patients with hematological malignancies at National Taiwan University Hospital is different from western countries in that Gram-negative bacteria remain the predominant pathogens. Antimicrobial resistance among these pathogens is high and E. coli and K. pneumoniae isolates with resistance to third-generation cephalosporins and ciprofloxacin are increasing.

R147W mutation of PROC gene is common in venous thrombotic patients in Taiwanese Chinese

We analyzed the genetic defects of 21 unrelated patients with venous thrombosis in whom hereditary protein C deficiency was diagnosed. Eleven mutations were detected in 18 families, while no mutation was detectable in the other three families. Among these mutations, a common genetic mutation of protein C (PROC) gene recurred in 43% (nine propositi from these 21 families). This C6152T mutation at exon 7 resulted in a missense mutation, Arg147Trp (R147W). Each propositus or family carrier had another specific polymorphism T66C at exon 2, which did not change the proline at position (-21). The haplotype analysis strongly suggested a founder effect. The first thrombotic attack was significantly younger in patients with multiple genetic defects or combined with other risk factors than those without precipitating factors. We further studied the prevalence rate of R147W mutations in normal populations through PCR amplification and dot hybridization. Three different cohorts got similar results. The prevalence rate of R147W in health controls is 0.85% [95% confidence interval (CI) 0.35-1.35]. Analysis of plasma protein C levels of all patients or carriers suggested that R147W was a type II deficiency. The odds ratio of thrombosis of R147W is 5.1 (95% CI 1.7-14.8). Taken together, R147W mutation is a significant thrombotic risk factor and is the most common defect of PROC gene in Taiwanese patients with protein C deficiency. This finding is important for screening thrombophilic families in Chinese populations.

A first Taiwanese Chinese family of type 2B von Willebrand disease with R1306W mutation

Clinical, laboratory and genetic defect of a Taiwanese family with type 2B von Willebrand disease (VWD) were studied. The proband was a 55-year-old woman who gave birth to two daughters and one son aged 30, 29 and 27, respectively. All had abnormal mucocutaneous bleedings since their childhood. In proband, PT, PTT and platelet count were normal; template bleeding time was 14 min; VIII:C was 51%, von Willebrand factor antigen (VWF:Ag), 42% and von Willerand factor ristocetin-cofactor (VWF:RCo, 15%); ristocetin-induced platelet aggregation (RIPA) at 0.3 and 0.6 mg/ml of ristocetin was 16% and 68%, respectively. The enhanced response to ristocetin was identified to be in plasma, not in platelet itself, by mixing studies. Analysis of von Willebrand factor (VWF) multimer of plasma but not of platelets showed absence of high-molecular weight (HMW) multimer. All three children had similar laboratory findings. Exon 28 of VWF gene was amplified using polymerase chain reaction (PCR) and sequenced. The proband and three children were all found to be heterozygous for C to T transition at nucleotide 3916 resulting in Arg 1306 Trp (R1306W) substitution. This mutation in the glycoprotein Ib (GPIb)-binding site has been found to increase the affinity of plasma VWF for platelets, and thus cause loss of HMW multimers and often thrombocytopenia. In conclusion, a first report of type 2B VWD in a Taiwanese Chinese family who show R1306W mutation in VWF gene was described.

Reduction of leukocyte count is associated with thalidomide response in treatment of multiple myeloma

Fifty Taiwanese patients with relapsed and/or refractory multiple myeloma (MM) were treated with thalidomide on a dose-escalation schedule, commencing with 100 mg/d nightly and incremented either to the maximally tolerated dose or 800 mg/d. Twenty-two patients (44%) responded, with 10 (45.5%) classified as partial remission and 12 (54.5%) minimal response (MR). Complete response did not occur. Of the 28 non-responders, 14 were progressive disease and 14 stable. The median time from commencement of thalidomide treatment to initial achievement of MR was 29 days (range, 8~155), and the corresponding thalidomide dose was 200 mg/d (range, 100~500). The median tolerated dose of thalidomide for the entire sample was 400 mg/d (range, 100~800), with only two (4%) able to tolerate 800 mg/d. Comparing responsive and non-responsive patients, statistically significant differences were not demonstrated for any characteristics except for CRP level and percentage cytogenetic change, which was slightly higher in the latter group relative to the former. Of particular interest, 18 of the 22 responders experienced transient reduction of leukocyte count preceding the attainment of significant reduction in M-proteins in comparison to only four of the 28 non-responders (82% vs. 14%; p<0.001). The median time from commencement of thalidomide treatment to attainment of minimal leukocyte count was 28 days (range, 7~150), with a mean of 2.19x10(9)/l (range, 0.96~3.35x10(9)/l). Leukopenia was generally transient, with rapid recovery despite subsequent continuation of thalidomide. Levels of other non-hematologically adverse effects attributed solely to thalidomide were generally acceptable. For 25 patients, thalidomide treatment was supplemented with low-dose dexamethasone (4 mg, every other day). Of these, 11 had relapsed from and 14 were primarily refractory to thalidomide treatment. Nine of the 25 dexamethasone-supplemented patients were responders (36%). Of particular note were the unusual events noted with this thalidomide-dexamethasone combination, including vascular thrombosis, acute cholecystitis, idiopathic interstitial lung disease and sudden cardiac death. Our results suggest that thalidomide is also effective for Taiwanese patients with refractory and/or relapsed MM. Importantly, the transient reduction in leukocyte count after commencement of thalidomide treatment may serve as a clinical predictor for response. Adverse effects should be carefully monitored when combining thalidomide and dexamethasone, however.

SOCS1 methylation in patients with newly diagnosed acute myeloid leukemia

The proliferation and differentiation of hematopoietic precursor cells depend on various cytokines. The suppressor of cytokine signaling-1 (SOCS1) down-regulates Janus kinases/signal transducers and activators of transcription (JAK/STAT) pathway activity and inhibits the biological effects of cytokines. SOCS1 has been shown to have tumor-suppressor activity, and methylation of this gene, resulting in transcriptional silencing, has been found in 65% of hepatocellular carcinoma and has been suggested to play an important role in the development of the cancer. The methylation status of the SOCS1 gene in acute myeloid leukemia (AML) has not been reported before. In this study, we analyzed SOCS1 methylation in 89 patients with newly diagnosed AML and correlated the result with immunophenotypes, cytogenetics, clinical features, and treatment outcome. SOCS1 methylation was found in the leukemic cells from 53 patients (60%). Thirteen (76%) of the 17 patients with t(15;17) had SOCS1 methylation, whereas this gene was methylated in only one (11%) of the nine patients with t(8;21). The frequencies of SOCS1 methylation among various cytogenetic subgroups differed significantly (P = 0.014). Other clinical and laboratory parameters and the disease-free survival and overall survival were similar between patients with and without SOCS1 methylation. In conclusion, SOCS1 methylation occurs in more than half of AML cases, correlates with cytogenetic abnormalities, and may play an important role in the development of subsets of AML.

Discontinuous residues of factor IX constitute a surface for binding the anti-factor IX monoclonal antibody A-5

Anti-human factor IX monoclonal antibody, A-5 (Mab A-5), has been widely used in structure-function studies for factor IX. Mab A-5 recognizes the catalytic domain of human factor IX (FIX). Regions important for Mab A-5 binding have previously been localized to the amino terminus of the heavy chain of factor IX, encompassing amino acid residues 181-310 [Blood (74) 971]. We have selected 20 positions in this region for alanine-scanning mutagenesis. We found that Mab A-5 failed to react with the recombinant factor IX mutants with substitutions at positions 228 and 252. Mab A-5 also reacted to a lesser extent to FIXD276A (factor IX with alanine substitution for aspartic acid at residue 276) and FIXK201A/D203A (double alanine substitutions at residues 201 and 203). The apparent dissociation rate constants (K(D)) in binding Mab A-5 were 6.0 x 10(-9), 1.4 x 10(-8) and 2.0 x 10(-8) M, for wild-type FIX, FIXK201A/D203A and FIXD276A, respectively. The increased K(D) values of the two FIX mutants are mainly owing to the increased dissociation rates. These affected residues constitute a surface opposite from the factor VIIIa binding surface. We conclude that the epitope for Mab A-5 is on a surface composed of residues 228, 252, 276, and 201 or 203. This surface, which may not be important for factor VIII binding, contains a strong antigenic region on factor IX.

High incidence of CD56 expression and relapse rate in acute myeloid leukemia patients with t(8;21) in Taiwan

BACKGROUND AND PURPOSE

CD56 is a marker of natural killer cells, but can also be found on blast cells in acute myeloid leukemia (AML). The prognostic implications of CD56 expression in AML are not clear. In this study, we evaluated the correlation among CD56 expression, cytogenetic abnormality, and clinical outcome in AML.

METHODS

CD56 expression was analyzed in leukemic cells from 94 adults with primary AML in Taiwan and was correlated with clinical and hematologic features, cytogenetics, and immunophenotypes of the leukemia.

RESULTS

Thirty patients (32%) showed CD56 expression. CD56+ AML patients had a higher lactate dehydrogenase level than CD56- patients (1.136 vs 730 V/L, p = 0.048). Patients with t(8;21) had a significantly higher incidence (89%, 8/9) of CD56 positivity in leukemic cells than those with normal karyotype or other cytogenetic abnormalities (26%, 22/85, p < 0.001). In general, there was no difference in overall survival time in CD56+ and CD56- AML patients. However, three patients had central nervous system involvement at initial presentation; two of these had concomitant CD56 expression and t(8;21). In addition, five of the seven patients with t(8;21) and CD56 expression who achieved complete remission later relapsed.

CONCLUSIONS

The incidence of CD56 expression in AML patients with t(8;21) is very high in Taiwan, and it may imply a poor prognosis in this subgroup of patients.