GFI1B Mutation Causes a Platelet Function Defect With Reduced Alpha-Granule Content and Abnormal Aggregation Response

Abstract GFI1B is a transcription factor important for erythropoiesis and megakaryocyte development, but previously unknown to be associated with human disease. We have identified a family with an autosomal dominant bleeding disorder associated with thrombocytopenia, red cell anisopoikilocytosis and platelet dysfunction. The severity of bleeding is variable with some affected individuals experiencing spontaneous bleeding while other family members only exhibit abnormal bleeding with surgery. All affected individuals had a moderate thrombocytopenia ranging from 72-149 x109/L with an elevated mean platelet volume. Platelet function was perturbed with prolonged collagen/epinephrine closure times on the PFA-100 (294 vs 125 sec, P <0.001). Platelet aggregation studies were abnormal, with an absent collagen response and primary aggregation only with ADP, arachidonic acid and adrenaline. Genetic linkage analysis and massively parallel sequencing were performed on 16 family members to localize the mutation causing the disease phenotype to chromosome 9. A single nucleotide insertion was identified in GFI1B that predicts a frameshift mutation in the fifth zinc finger DNA-binding domain. This mutation alters the transcriptional activity of the protein as determined by luciferase production from the TGFBR3 and GFI1B promoters. Aberrant transcriptional activity was associated with a marked reduction in platelet alpha-granule content as measured by electron microscopy (1.3 vs 3.1 alpha-granules per 1µm2, P<0.001) with similar changes in platelet protein expression. Proteomic analysis of platelet lysates demonstrated altered levels of cytoskeletal proteins, including talin, vinculin and myosin light chain 6. GFI1B mutation represents a novel human bleeding disorder and the described phenotype identifies GFI1B as a critical regulator of platelet number and function. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Hereditary Thrombocytosis Caused By a Novel Germ-Line Mutation In The Gelsolin Gene

Blood ◽

10.1182/blood.v122.21.265.265 ◽

2013 ◽

Vol 122 (21) ◽

pp. 265-265 ◽

Cited By ~ 1

Author(s):

Annalisa Pianta ◽

Kun Liu ◽

Pontus Lundberg ◽

Takafumi Shimizu ◽

Hui Hao-Shen ◽

...

Keyword(s):

Germ Line ◽

Conflicts Of Interest ◽

Family Members ◽

Chromosome 9 ◽

In Vitro Assays ◽

Candidate Mutation ◽

Genome Wide ◽

Germ Line Mutation

Abstract Hereditary thrombocytosis (HT) is a familial myeloproliferative disorder with clinical features resembling sporadic essential thrombocythemia. In some families germline mutations causing HT have been identified in the genes for thrombopoietin (THPO) and its receptor, MPL. However, in many HT families the disease-causing genetic lesion remains unknown. Here we studied a HT pedigree with 15 affected family members in 5 generations. Thrombocytosis is transmitted as an autosomal dominant trait with high penetrance (Figure 1). Genome-wide linkage analysis was performed on DNA from 21 family members using microsatellites and single nucleotide polymorphism arrays. A single co-segregating region with a LOD score of 4.3 was found on chromosome 9. All exons and splice junctions of genes within the co-segregating region were sequenced by classical DNA sequencing and by Next Generation Sequencing (Illumina). We found a candidate mutation in the gelsolin gene (GSN). This C/T transversion was not reported in any SNP database. Computational analysis predicts that the resulting Gly to Cys amino acid change will be damaging to the protein structure. Platelet biogenesis in vitro assays in DAMI cell line stably transfected with the mutant GSN showed that the candidate alteration increased the release of platelets-like particles. To study the in vivo role of the candidate mutation, we generated transgenic mice expressing the mutant GSN gene. These mice developed thrombocytosis and showed increased numbers of megakaryocytes in bone marrow (Figure 2). Thus, our genetic and functional data strongly suggest that GSN mutation is causing thrombocytosis in this family. The exact mechanism of how this newly identified genetic alteration leads to increased megakaryopoiesis needs further investigation. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

P 736. Benign Enlargement of Subarachnideal Spaces and Subdural Hematoma in an Infant: Spontaneous Bleeding, Child Abuse, or Bleeding Disorder?

10.1055/s-0038-1675972 ◽

2018 ◽

Author(s):

Kristine Adam ◽

Leo Rossler ◽

Christine Decker ◽

Charlotte Thiels ◽

Christoph Heyer ◽

...

Keyword(s):

Child Abuse ◽

Subdural Hematoma ◽

Bleeding Disorder ◽

Spontaneous Bleeding

Download Full-text

Absence of the Complete Platelet-Specific Alloantigens Zw (PlA) On Platelets in Glanzmann’S Thrombasthenia and the Effect of Anti-Zwa Antibody on Platelet-Function

10.1055/s-0039-1687067 ◽

1979 ◽

Author(s):

E.F. von Leeuwen ◽

G.T.E. Zonneveld ◽

L.E. von Riesz ◽

C.S.P Jenkins ◽

J.A. van Mourik ◽

...

Keyword(s):

Platelet Function ◽

Gel Electrophoresis ◽

Family Members ◽

Glanzmann’S Thrombasthenia ◽

Platelet Membranes ◽

Glanzmann's Thrombasthenia ◽

The Family ◽

Induced Aggregation ◽

Aggregation Of Platelets ◽

Slight Inhibition

The expression of the platelet-speciftc alloantigens on the platelets from 6 patients with Glanzmann’s Thrombasthenia (G.T.) and their nearest relatives was studied. The alloantigens Zwa (PIAl) and Zwb(PIA2) were found to be completely absent from thrombasthenic platelets while the alloantigens of the Ko-system were found to be normally expressed. The alloantigen Baka(phenotypefrequency 90.2%) was absent on the platelets from 4 studied G.T. patients. The platelets of all the family members reacted positively with anti-Zwa, negatively with antt-Zwb serum. SDS-PA gel electrophoresis of G.T. platelet membranes demonstrated a marked deficiency of the glycoproteins IIb and IIIa. Glycoprotein analysis of the platelet membranes from the family members of 3 of the 6 patients reveoled no apparent abnormalities.Pre-incubation with anti-Zwa containing plasma strongly inhibits ADP-and collagen induced aggregation of platelets from normal Zwa homozygous individuols with a slight inhibition of the aggregation induced by ristocetin. Zwa antibodies did not affect the functions of platelets from ZWb homozygous individuals. Thus binding of Zwa antibodies induces a thrombosthenis-like state.

Download Full-text

Rab38 Expression in Platelet Dense Granule Storage Pool Disease.

Blood ◽

10.1182/blood.v110.11.2112.2112 ◽

2007 ◽

Vol 110 (11) ◽

pp. 2112-2112

Author(s):

Ivana Ninkovic ◽

James G. White ◽

Kenyatta W. Stephens ◽

Artur Rangel-Fihlo ◽

Francsisca C. Wu ◽

...

Keyword(s):

Platelet Aggregation ◽

Platelet Function ◽

Flow Cytometric Analysis ◽

Dense Granule ◽

Bleeding Disorder ◽

Coding Region ◽

Platelet Dysfunction ◽

Granule Formation ◽

Storage Pool ◽

Storage Pool Disease

Abstract Platelet dense granule storage pool disease (SPD) is a bleeding disorder characterized by a lack of normal platelet dense granule function, as evidenced by decreased platelet aggregation in response to ADP, epinephrine and collagen. Platelet SPD has been studied most extensively in humans and rodents with Hermansky-Pudlak syndrome (HPS), whose phenotype is a result of defects in granule trafficking, leading to oculocutanous albinism, lysosomal storage diseases, and platelet dysfunction. We have been characterizing the fawn-hooded hypertensive (FHH) rat, which has been previously shown to have a bleeding disorder consistent with a platelet SPD and some of the features of HPS. While the platelets in the FHH rat have normal alpha granules and lysosomes, they lack dense granules as assessed by transmission electron microscopy. Platelet flow cytometric analysis of GPIb and GPIIb indicated that the FHH platelets have normal surface expression of these adhesion proteins. The FHH rat has a mutation in the Rab38 gene at the ATG start site, which is associated with the bleeding disorder. Rab38 is part of a large family of GTPases, which are involved in granule formation and secretion. Western blotting of FHH tissues revealed that there is no expression of Rab38 protein. We have used confocal immunomicroscopy to assess Rab38 in platelet formation and function. In normal rat and human platelets, there was punctate expression of Rab38. There was no Rab38 staining detected in FHH platelets. In human megakaryocytic cell lines, Dami and HEL cells, there was punctate staining of Rab38 that was mainly in the periphery of the cells, with a variable amount of perinuclear staining. There was partial colocalization of Rab38 with serotonin and VWF, and with Lamp-3, a marker of lysosomes. The degree of colocalization varied between cells. There was no clear association of Rab38 with actin and tubulin in megakaryocytes. We also examined a cohort of patients with SPD, but not HPS, for mutations in Rab38. The entire coding region and intron-exon boundaries of the Rab38 gene were sequenced in 18 patient samples collected at Emory University for the CDC Women with Bleeding Disorders and Menorrhagia Study. Ten of the patients had platelet function defects documented by standard platelet aggregation studies, and eight had no identifiable platelet function defect. No mutations in Rab38 were detected. Whereas numerous known polymorphisms were identified and confirmed, there was no association of any of them with platelet function abnormalities. In conclusion, Rab38 is expressed in platelets and megakaryocytes and may interact with other granule proteins during megakaryocyte development. Failure to express Rab38 is associated with platelet dysfunction. Further studies are needed to determine its function in megakaryocytes and platelets, and to determine whether defects in Rab38 are a cause of platelet SPD in humans.

Download Full-text

The Power of a Standardized Bleeding Score in Diagnosing Pediatric Type 1 Von Willebrand Disease.

Blood ◽

10.1182/blood.v114.22.1293.1293 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1293-1293

Author(s):

Paul D Marcus ◽

Kidan G Nire ◽

Linda Grooms ◽

Jennifer Klima ◽

Sarah O'Brien

Keyword(s):

Platelet Function ◽

Predictive Value ◽

Care Setting ◽

Tertiary Care ◽

Bleeding Disorder ◽

Von Willebrand Disease ◽

The Mean ◽

Bleeding Score ◽

Von Willebrand

Abstract Abstract 1293 Poster Board I-315 INTRODUCTION Type I von Willebrand disease (VWD) is the most common inherited bleeding disorder. Repetitive testing of von Willebrand factor (VWF) levels is necessary before the diagnosis can be safely ruled out, as VWF levels fluctuate in response to genetic and environmental factors. A predictive bleeding score (BS) could reveal individuals that may benefit from repetitive testing and those for whom repetitive testing is unlikely to be of benefit. While a standardized questionnaire (the Vicenza score) was developed to evaluate hemorrhagic symptoms, it was never prospectively validated for a pediatric population in a tertiary care setting. SUBJECTS The study targeted children, ages 0 to 17 years, referred to the Hemostasis and Thrombosis Center (HTC) of Nationwide Children's Hospital for a coagulation evaluation as a result of bleeding symptoms, family history of a bleeding disorder and/or abnormal coagulation labs found during pre-operative screening. Children were excluded if they had a previously diagnosed bleeding disorder, if their caregiver did not speak English or if the child did not undergo VWF:Ag and VWF:RCo testing. METHODS Prior to the diagnosis or exclusion of a bleeding disorder in the child, caregivers consented to answer the questionnaire over the telephone. Descriptions of the Vicenza score are available online (http://www.euvwd.group.shef.ac.uk/bleed_score.htm). LABORATORY TESTING A single VWF:Ag or VWF:RCo <30 IU/dL was classified as “Definite Type 1 VWD” while levels from 30-50 IU/dL were classified as “Low VWF” (http://www.nhlbi.nih.gov/guidelines/vwd). Platelet function analysis (PFA-100) screened for platelet function defects, with some patients undergoing follow-up platelet aggregation studies and/or platelet electron microscopy. Laboratory studies from other institutions were excluded from analysis. Patients' medical records were reviewed after hematologic evaluation, and the resultant data was analyzed with STATA 10.1 (Stata Corp., College Station, TX). RESULTS A total of 104 children (52 females and 52 males) with a mean age of 7.53 years (range 1 month to 17 years) were included. At least one hemorrhagic symptom was present in 99 of the 104 children (95%) with the mean number of symptoms being 2.87 (range 0 to 7). The mean Vicenza score was 3.24 (range -1 to 13). Of the 104 children, 8 met criteria for “Definite Type 1 VWD,” 23 met criteria for “Low VWF,” 14 were diagnosed with a “Platelet Function Defect,” and 2 children had bleeding secondary to Ehlers Danlos syndrome. Children with non-bleeding disorders (e.g. Factor XII deficiency) or no laboratory evidence of a bleeding disorder were classified as “No Bleeding Disorder.” In general, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and positive diagnostic likelihood ratio of the bleeding questionnaire demonstrated poor predictive value in our patient population with the exception of high specificity in ruling out “Definite Type 1 VWD” (Table). The NPV was comparably high with both qualitative (>2 bleeding symptoms) and quantitative (BS ≥2) criteria. CONCLUSIONS The Vicenza score, previously validated in adults and in a pediatric primary care setting, appears to have limited predictive value in a pediatric tertiary care setting when evaluating patients with platelet function defects or low VWF levels. While the Vicenza score has a high NPV to exclude “Definite Type 1 VWD,” the use of simpler qualitative criteria is similarly predictive. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Inhibition of Platelet Function by Aspirin in Insulin Dependent Diabetics without Vascular Disease.

Blood ◽

10.1182/blood.v114.22.4172.4172 ◽

2009 ◽

Vol 114 (22) ◽

pp. 4172-4172

Author(s):

Kenneth A. Schwartz ◽

Dianne E Schwartz ◽

Anjana Myneni ◽

Peggy Nelson ◽

Ved Gossain

Keyword(s):

Vascular Disease ◽

Platelet Function ◽

Clinical Evidence ◽

Conflicts Of Interest ◽

Platelet Inhibition ◽

Diabetic Patients ◽

Platelet Production ◽

Occlusive Vascular Disease ◽

Insulin Dependent ◽

Normal Controls

Abstract Abstract 4172 Diseases like diabetes that are associated with increased platelet production are reported to have decrease aspirin (ASA) induced platelet inhibition. ASA inhibition of platelet function is mediated via acetylation of platelet cylooxygenase, which is completed approximately 30 minutes after ingestion. Thereafter production of new non-acetylated platelets increases the proportion of normal platelets gradually reversing ASA platelet inhibition. We tested the hypothesis that insulin dependent diabetics (type 1) without clinical evidence of occlusive vascular disease have less aspirin platelet inhibition than normal controls. The amount of ASA (325mg) platelet inhibition was measured using the slope (S) of platelet prostaglandin agonist (PPA) stimulated light aggregation curve that decreases after ASA. Aggregation was measured at 3 time points: before ASA ingestion, time 0 (T0); 2 hours post ASA (T2); and 24 hours after ASA (T24). Percent recovery from aspirin inhibition was calculated using the formula (T24–T2)/ (T0-T2) x100. Eight adult insulin dependent diabetic patients without clinical evidence of vascular disease and who were not taking aspirin were compared with 11 nondiabetic controls. 24 hours after aspirin ingestion diabetic patients recovered 10% of their maximal ASA platelet inhibition compared to 13% in controls (p=0.69). We conclude that recovery of platelet function from ASA in insulin dependent diabetics without clinical vascular disease occurs at the same rate as normal controls, suggesting that the previously reported decrease in platelet inhibition in diabetic patients may be related to increased platelet production associated with clinically evident occlusive vascular disease. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

A New Model of Care: A Combined Pediatric/ Adult Thrombosis and Hemostasis (PATH) Clinic – One Center's Experience.

Blood ◽

10.1182/blood.v114.22.4553.4553 ◽

2009 ◽

Vol 114 (22) ◽

pp. 4553-4553

Author(s):

Matthew W Richardson ◽

Richard H Steingart

Keyword(s):

Chart Review ◽

Conflicts Of Interest ◽

Asymptomatic Patient ◽

Family Members ◽

Model Of Care ◽

Adult Age ◽

Adolescent Women ◽

Simultaneous Evaluation ◽

Recent Diagnosis ◽

Developmental Traits

Abstract Abstract 4553 Background Patients of all ages with thrombosis are frequently tested for heritable thrombophilias (HT). Similarly, patients with bleeding or bruising may be tested for heritable bleeding (HB) conditions. We developed the Pediatric/Adult Thrombosis & Hemostasis (PATH) Clinic, a once-monthly clinic where children, adults and their families in whom the diagnosis of HT or HB was established or being considered could be assessed simultaneously by a pediatric and “adult” hematologist. Reasons for the clinic's creation included 1. HT/ HB conditions are lifelong. A combined clinic aids transition from a pediatric provider to an internist at the same institution. 2. Adolescence is when many HT/ HB disorders manifest themselves. This group has medical and developmental traits that cross pediatric and internal medicine approaches and expertise. 3. Adult experience. Much treatment for pediatric thromboses is extrapolated from adult data. An adult hematologist present at the evaluation of a pediatric patient with HT provides a valuable resource for the child and pediatric hematologist. 4. The finding of HT or HB in a patient has implications for family members regardless of age. 5. Convenience. All family members can be evaluated at a single visit where several members might need screening. Objective To review the experience of a combined pediatric/adult clinic created to evaluate potential HT/ HB in patients of all ages. Method IRB-approved chart review. Results 92 patients have been evaluated (61 for HT, 31 HB). Mean age 18 yr., median 16 yr. Female 64%. The most common reason for referral was evaluation of HT in an asymptomatic patient (42%) because of a family member having had a thrombosis or recent diagnosis of HT. Those evaluated for potential HT were less likely to be symptomatic (i.e. had not experienced a thrombosis) than those with HB (31% vs. 65%, p < 0.01). Adolescents (13–21 yr old) comprised 52% of all patients (57% of all females). Adolescents were more likely to be referred for HT than other ages (75% vs. 56%, p < 0.01). Conclusions The model of the PATH clinic – simultaneous evaluation of patients of all ages with or suspicion for HT/ HB by a pediatric and “adult” hematologist – may be useful to other centers. Adolescents (in transition from the pediatric to adult age group) comprised the single largest cohort, emphasizing the potential importance of a combined approach. Adolescent women were especially represented, likely due to the new potential for bleeding (menarche) leading to a diagnosis of an HB and the emergence of acquired thrombophilic risk factors (estrogen contraception and pregnancy) in this group that have implications in families with HT. Physicians in such a clinic should have particular knowledge of bleeding and thrombophilic conditions in adolescent women and of counseling for asymptomatic HT. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Correlation of a Condensed Bleeding Score with New Diagnosis of a Congenital Bleeding Disorder in Patients Referred to a Tertiary Centre

Blood ◽

10.1182/blood.v118.21.1226.1226 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1226-1226

Author(s):

Deepa Ranjani Jayakody Arachchillage ◽

Tina Biss ◽

John Hanley ◽

Kate Talks

Keyword(s):

Laboratory Tests ◽

Conflicts Of Interest ◽

Bleeding Disorder ◽

Bleeding Tendency ◽

Factor Xi ◽

Factor Xi Deficiency ◽

Number Of Patients ◽

Abnormal Bleeding ◽

Bleeding Score

Abstract Abstract 1226 The performance and utility of a condensed bleeding score (Bowman et al, J Thromb Haemost., 2008;6:2062) in relation to the diagnosis of a congenital bleeding disorder in new referrals to a regional haemostasis clinic over an 8 month period is presented. Between November 2010 and June 2011, 50 patients over the age of 16 (median age, 31 years; range, 16–79), including 32 females, were referred for investigation of a possible congenital bleeding disorder following detection of abnormal coagulation results and/or presentation with a bleeding history. A bleeding score was performed as part of their initial assessment. 12(24%) patients were from local referral and 38(76%) patients were referred from other hospitals in the region for further investigation of a suspected bleeding disorder. Basic coagulation tests (activated partial thromboplastin time (APTT), prothrombin time Clauss fibrinogen and platelet count) were normal in the referred patients from other centres. 50% (6/12) of the local referrals were for investigation of a prolonged APTT detected on routine coagulation screening prior to major surgery. The median bleeding score was 6 with a range of −1 to 14 (Table 1). The presence of a congenital bleeding disorder was confirmed in 31 of the 50 patients (62%), including 19/31 (61%) of the female patients and 12/31(39%) of the males. Correlation of an abnormal bleeding score (score ≥ 4) with diagnosis of a congenital bleeding disorder was only seen for diagnosis of type 1 Von Willebrand Disease (VWD) (Table 2). Analysis of the cases with low scores and abnormal results identified two groups of patients; firstly, those who had not yet had a significant haemostatic challenge, and secondly, those in whom the abnormal coagulation results were explained by a non-haemostatically significant reduction in a coagulation factor level (e.g. FVII, 15%; dysfibrinogenaemia; F XII deficiency). These clinically insignificant laboratory abnormalities explain the discrepancy between the number of patients with abnormal laboratory tests (35) and the number of patients diagnosed with a congenital bleeding disorder (31).Table 1Bleeding score (range)Number of patients with normal lab resultsNumber of patients with abnormal lab results−1 to +1382–44105–74128–102311–1422Total1535Table 2DiagnosisNumber of patientsMedian bleeding scoreAge rangeType 1 VWD116 (4–10)17–51Type 2 VWD48 (5–13)17–36Factor XI123 (1–8)17–76Platelet function defect46 (2–9)17–57 Compared to previous reports the range of scores found with this assessment tool was narrow and could not exclude patients from further laboratory assessment. However the condensed bleeding score has only been validated prospectively for the diagnosis of type 1 VWD and all patients in this cohort who were diagnosed with type 1 VWD had an abnormal bleeding score (≥ 4). This observation supports the role of this scoring system in the assessment of patients for type 1 VWD. The use of the condensed bleeding score in assessing patients with suspected factor XI deficiency is difficult due to the lack of a phenotypic relationship between residual factor XI activity and a bleeding tendency. Furthermore, although factor XI deficiency is a rare congenital bleeding disorder in our cohort of patients 12/31(39%) were diagnosed with factor XI deficiency. This may explain the overall lack of correlation between bleeding score and diagnosis of a congenital bleeding disorder. Patients who have an abnormal bleeding score but normal laboratory tests need consideration of further investigations before concluding they are normal. The possibility of an acquired bleeding disorder should be considered. A thorough drug history is also important as one of the patients with a bleeding score of 14 was taking a non-steroidal anti-inflammatory drug. The use of the condensed bleeding score in the detection of congenital bleeding disorders other than type 1 VWD requires further validation in a larger number of patients. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Noval Mutation in Four Saudi Families with Glanzmann Thrombasthenia

Blood ◽

10.1182/blood.v118.21.1136.1136 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1136-1136

Author(s):

Tarek Owaidah ◽

Hala Abalkhail ◽

Abdulrahman Al Musa ◽

Hasan Mosmali ◽

Albanyan Abdulmajeed ◽

...

Keyword(s):

Conflicts Of Interest ◽

Stop Codon ◽

Direct Sequencing ◽

Family Members ◽

Premature Stop Codon ◽

Type I ◽

Bleeding Tendency ◽

Coding Region ◽

Glanzmann Thrombasthenia ◽

Exon 1

Abstract Abstract 1136 Introduction: Glanzmann thrombasthenia (GT) is a rare autosomal recessive inherited bleeding disorder characterized by an impaired platelet aggregation and variable bleeding tendency. Inherited genetic mutations in integrin alpha IIb and beta3 (ITGA2B, ITGB3) result in a heterogeneity of the thrombasthenia phenotypes. It is phenotypically expressed in homozygotes or compound heterozygotes, given that 50% of normal aIIbb3 is sufficient to guarantee unimpaired platelet function that result in asymptomatic carriers. Defects in ITGB3 result in failure of binding of B3 and alpha IIb. These defects had been reported in Arabs (Iraqi Jews). We are reporting some results of Saudi GT genotype project. Materials & Methods: In this study, we analyzed the entire coding region ITGB3 gene using polymerase chain reaction (PCR) and direct sequencing with primers specifically designed to amplify the coding region of exon 1–15 and exon /Intron boundaries in a cohort of 51 GT patients diagnosed and treated in our institute. Results: Out of 51 cases from 20 families had mutational screening of the ITGB3 gene with the aim to detect the causative pathogenic mutations to enable the pre-symptomatic diagnosis in at risk family members. In this study we detect 1 novel germline mutation c.2190delC (p.Ser703fs) in exon 13. The mutation is predicted to result in premature stop codon and protein truncation. The mutation was detected in 6 patients in homozygous stat (3 males and 3 females). Three tested samples from the patients family members detected the mutation in heterozygous state and all of them were asymptomatic with normal PFA and Intact expression of Platelet Glycoprotiens CD41(Gpllb), CD42a(GPIX), CD42b(GPlb), and CD61(Gpllla). All the GT patients with this mutation were type I GT with Prolonged PFA and complete absence of CD41(Gpllb) and CD61(Gpllla) glycoprotein. Conclusion: The result of this study represents the first Molecular analysis of ITGB3 gene in Saudi Arabia and displays the existence of novel pathogenic and possibly a founder effect in Saudi families. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

An Increase in Factor VIII Levels with Increasing Age in a Subgroup of Individuals with Mild Hemophilia A

Blood ◽

10.1182/blood.v118.21.2278.2278 ◽

2011 ◽

Vol 118 (21) ◽

pp. 2278-2278 ◽

Cited By ~ 2

Author(s):

Lauren J Lee ◽

John K. Wu ◽

Man-Chiu Poon ◽

Shannon Jackson

Keyword(s):

Hepatitis C ◽

Factor Viii ◽

Medical Records ◽

Hemophilia A ◽

Conflicts Of Interest ◽

Bleeding Disorder ◽

Physiological Age ◽

Management Options ◽

Southern Alberta ◽

The Mean

Abstract Abstract 2278 Background: Hemophilia A is an X-linked hereditary disorder resulting in absent or reduced levels of functional factor VIII (FVIII:C). The baseline FVIII:C levels are important in the determination of treatment and management options in individuals with mild hemophilia who by definition exhibit FVIII:C levels between 6–40 U/dL. In individuals without hemophilia, FVIII:C increases with physiological age and this trend has not been well characterized in mild hemophilia. This is important to consider in mild hemophilia because treatment with factor concentrate or DDAVP may paradoxically increase the risk of venous or arterial thrombosis in older patients. Objectives: To describe the changes in baseline FVIII:C levels with time in a cohort of pediatric and adult subjects with mild hemophilia registered in the British Columbia Provincial and Southern Alberta Bleeding Disorder programs. Methods: All medical records for subjects with FVIII:C levels 6–40 U/dL registered with the BC Provincial and Southern Alberta Bleeding Disorder programs were reviewed for eligibility. Male subjects with a minimum of 2 FVIII:C level measurements at least 5 years apart were included in the analysis. Retrospective data was extracted from database/medical records, including age, gender, blood group, FVIII mutation, historical FVIII:C levels, historical DDAVP response (>3 fold and/or >50 U/dL), and co-infection (Hepatitis C, B and HIV) status. Linear mixed effects regression models were used to examine time trend of FVIII:C levels and subjects were stratified into 3 groups based on baseline FVIII:C (FVIII:C<15 U/dL, 15–24 U/dL, and ≥25 U/dL). Results: 198 records were reviewed and 116 subjects excluded from the analysis (chart unavailable, n=28; inadequate FVIII:C data, n=79; female, n=9) leaving 82 subjects who met eligibility criteria. The mean age at first FVIII:C measurement was 24.0 years (SD 19.6; Range 0.0–77.8). The mean follow-up time was 16.5 years (SD 19.6; Range 4.8–44.8). There was no observable trend of FVIII:C with time in the primary analysis of the whole cohort (p=0.667). However, for subjects with baseline FVIII:C<15 U/dL, who were ≥25 years of age (n=31), an increase in baseline FVIII:C levels of 0.11 percent per year (p<0.05) was observed. Subjects with baseline FVIII:C<15 U/dL (n=40) also showed less FVIII:C variability between measurements than subjects with FVIII:C≥15 U/dL (n=42). Subjects with baseline FVIII:C≥25 U/dL (n=18) demonstrated a decreasing trend of −0.15 percent per year (p<0.05), however also demonstrated the greatest variability between FVIII:C measurements. Co-infections were present in 24% (n=20) of subjects and included Hepatitis C (n=18), Hepatitis B (n=1), HIV (n=1). 73 subjects had known DDAVP response; >3-fold but ≤50 U/dL (n=11), ≤3-fold but >50 U/dL (n=15), >3-fold & >50 U/dL (n=23), ≤3-fold & ≤50 U/dL (n=24). Conclusion: This study suggests that there is an increase in FVIII:C with time in the subgroup of individuals with mild hemophilia ≥25 years of age and baseline FVIII:C levels <15 U/dL. Further long-term data particularly in the older cohort of subjects is needed to confirm this preliminary finding and further characterize this trend in subgroups with different baseline FVIII:C. Disclosures: No relevant conflicts of interest to declare.

Download Full-text