A Compound Heterozygosis of Two Novel Mutations Causes Factor X Deficiency in a Chinese Pedigree.

BACKGROUND: Mutations in the F10-coding gene can cause factor X (FX) deficiency, leading to abnormal coagulation activity and severe tendency for hemorrhage. Therefore, identifying mutations in F10 is important for diagnosing congenital FX deficiency. METHODS: We studied a 63-year-old male patient with FX deficiency and 10 of his family members. Clotting and immunological methods were used to determine activated partial thromboplastin time (aPTT), prothrombin time (PT), thrombin time (TT), fibrinogen levels, FX activity, and FX antigen levels. The platelet count was determined. A mixing study was performed to eliminate the presence of coagulation factor inhibitors and lupus anticoagulant. Mutations were searched using whole-exome sequencing and certified by Sanger sequencing. RESULTS: Genetic analysis of the proband identified two single-base substitutions: c.1085G>A (p.Ser362Asn) and c.1152C>A (p.Tyr384Ter, termination codon, caused by the DNA sequence TAA). His FX activity and antigen levels were 1.7% and 408.53 pg/mL, respectively; aPTT and PT were 52.3 and 48.0 s, respectively. One brother had the same compound heterozygous mutations, and his FX activity and antigen levels were 1.3% and 465.47 pg/mL, respectively; his aPTT and PT were 65.2 and 54.5 s, respectively. His mother, another brother, and one sister were heterozygous for c.1085G>A (p.Ser362Asn), and his daughter and grandson (6 years old) were heterozygous for c.1152C>A (p.Tyr384Ter). CONCLUSION: The heterozygous variants p.Ser362Asn or p.Tyr384Ter indicate mild FX deficiency, but the compound heterozygous mutation of the two causes severe congenital FX deficiency and bleeding. Genetic analysis of these two mutations may help characterize the bleeding tendency and confirm congenital FX deficiency.

Genetic analysis of a compound heterozygous patient with congenital factor X deficiency and regular replacement therapy with a prothrombin complex concentrate.

Congenital factor X (FX) deficiency is a rare bleeding disorder with an incidence of one in one million. The proband, a 2-year-old girl, exhibited easy bruising and a history of umbilical cord bleeding at birth. Prothrombin time (> 40 s) and activated partial thromboplastin time (65.0 s) were prolonged. Marked declines in FX activity (< 1%) and FX antigen levels (5%) were also observed. Genetic analysis of the proband identified two types of single-base substitutions, c.353G>A (p.Gly118Asp) and c.1303G>A (p.Gly435Ser), indicating compound heterozygous congenital FX deficiency. Genetic analysis of family members revealed that her father and older sister (5-year-old) were also heterozygous for p.Gly118Asp, and that her mother was heterozygous for p.Gly435Ser. To improve the bleeding tendency, the proband received regular replacement of 500 units of PPSB-HT, a prothrombin complex concentrate (PCC). Following continued regular replacement of 500 units of PPSB-HT once per week, the proband has exhibited no bleeding tendencies and no new bruises have been observed. There are no previous report of the use of PPSB-HT for regular FX replacement. Regular replacement therapy with PPSB-HT may be an effective method for preventative control of bleeding tendencies in FX deficiency.

Cutaneous adverse event associated with vemurafenib in a 3-year-old pediatric patient with BRAF mutation-positive metastatic melanoma and factor X deficiency.

Malignant melanoma is very rare in childhood. The approach to diagnosis and treatment in children has been adopted from adult guidelines. Vemurafenib is indicated in adults with BRAF V600 mutation-positive stage IIIc/IV melanoma and causes cutaneous adverse events. We report on a 3-year-old child with recurrent, metastatic (bone) BRAF mutation-positive melanoma. He also had severe factor X deficiency. Four days after vemurafenib treatment, bilateral palpebral edema and violet-colored hyperpigmentation were observed. There was no objective response to vemurafenib; however, bone pain regressed slightly. Our patient is the youngest patient who received vemurafenib for BRAF V600 mutation-positive metastatic melanoma in the literature.

Complex formation with pentraxin-2 regulates factor X plasma levels and macrophage interactions.

Recently, we have identified scavenger receptor class A member I (SR-AI) as a receptor for coagulation factor X (FX), mediating the formation of an FX reservoir at the macrophage surface. Here, we demonstrate that the FX/SR-AI-complex comprises a third protein, pentraxin-2 (PTX2). The presence of PTX2 is essential to prevent internalization of FX by SR-AI, and the presence of FX is needed to interfere with internalization of PTX2. Binding studies showed that FX, SR-AI, and PTX2 independently bind to each other (KD,app: 0.2-0.7 µM). Surprisingly, immunoprecipitation experiments revealed that FX and PTX2 circulate as a complex in plasma, and complex formation involves the FX activation peptide. No binding of PTX2 to other vitamin K-dependent proteins was observed. Short hairpin RNA-mediated inhibition of PTX2 levels in mice resulted not only in reduced levels of PTX2, but also in similarly reduced FX levels. Moreover, PTX2 and FX levels were correspondingly reduced in SR-AI-deficient mice. Analysis of 71 human plasma samples uncovered a strong correlation between FX and PTX2 plasma levels. Furthermore, plasma samples of patients with reduced FX levels (congenital/acquired FX deficiency or after anti-vitamin K treatment) were characterized by concomitantly decreased PTX2 levels. In conclusion, we identified PTX2 as a novel partner for FX, and both proteins cooperate to prevent their SR-AI-mediated uptake by macrophages. Interestingly, their respective plasma levels are interdependent. These findings seem of relevance in perspective of ongoing clinical trials, in which plasma depletion of PTX2 is used as a therapeutical approach in the management of systemic amyloidosis.

Experience of a new high-purity factor X concentrate in subjects with hereditary factor X deficiency undergoing surgery.

INTRODUCTION: Maintaining haemostasis in surgery is challenging for hereditary rare bleeding disorders in which multi-coagulation-factor concentrates are the only therapeutic option. Hereditary factor X (FX) deficiency affects 1:500 000 to 1:1 000 000 individuals, and no specific replacement FX concentrate has been available. A high-purity, plasma-derived FX concentrate (pdFX) has been developed for patients with hereditary FX deficiency. AIM: Our objective was to assess the safety and efficacy of pdFX in subjects with FX deficiency undergoing surgery. METHODS: Subjects with hereditary mild-to-severe FX deficiency (basal plasma FX activity [FX:C] <20 IU dL(-1) ) undergoing surgery received pdFX preoperatively to raise FX:C to 70-90 IU dL(-1) and postoperatively to maintain levels >50 IU dL(-1) until the subject was no longer at risk of bleeding due to surgery. Efficacy of pdFX was assessed by blood loss during surgery, requirement for blood transfusion, postoperative bleeding from the surgical or other sites, and changes in haemoglobin levels. Safety was assessed by adverse events (AEs), development of inhibitors, and clinically significant changes in laboratory parameters. RESULTS: Five subjects (aged 14-59 years) underwent seven surgical procedures (four major and three minor). Treatment duration was 1-15 days. For each procedure, pdFX treatment was assessed as "excellent" in preventing bleeding and achieving haemostasis. No blood transfusions were required, no AEs related to pdFX were observed, and no clinically significant trends were found in any laboratory parameters. CONCLUSION: These data demonstrate that pdFX is safe and effective as replacement therapy in five subjects with mild-to-severe FX deficiency undergoing surgery on seven occasions.

Efficacy, safety and pharmacokinetics of a new high-purity factor X concentrate in subjects with hereditary factor X deficiency.

INTRODUCTION: Hereditary factor X (FX) deficiency is a rare bleeding disorder affecting 1:500 000 to 1:1 000 000 of individuals. Until recently, no specific replacement factor concentrate was available. AIM: The aim of this study was to assess safety and efficacy of a new, high-purity plasma-derived FX concentrate (pdFX) in subjects with hereditary FX deficiency. METHODS: Subjects aged ≥12 years with moderate or severe FX deficiency (plasma FX activity <5 IU dL(-1) ) received 25 IU kg(-1) pdFX as on-demand treatment or short-term prophylaxis for 6 months to 2 years. Subjects assessed pdFX efficacy for each bleed; at end-of-study, investigators assessed overall pdFX efficacy. Blood samples for pharmacokinetic analysis were obtained at baseline and ≥6 months. Safety was assessed by adverse events (AEs), inhibitor development and changes in laboratory parameters. RESULTS: Sixteen enrolled subjects (six aged 12-17 years; 10 aged 18-58 years) received a total of 468 pdFX infusions. In the 187 analysed bleeds, pdFX efficacy was categorized as excellent, good, poor or unassessable in 90.9%, 7.5%, 1.1% and 0.5% of bleeds respectively; 83% of bleeds were treated with one infusion. For pdFX, mean (median; interquartile range) incremental recovery and half-life were 2.00 (2.12; 1.79-2.37) IU dL(-1) per IU kg(-1) and 29.4 (28.6; 25.8-33.1) h respectively. No serious AEs possibly related to pdFX or evidence of FX inhibitors were observed, and no hypersensitivity reactions or clinically significant trends were detected in laboratory parameters. CONCLUSION: These results demonstrate that a dose of 25 IU kg(-1) pdFX is safe and efficacious for on-demand treatment and short-term prophylaxis in subjects with moderate or severe hereditary FX deficiency.

Intracranial Hemorrhage as the First Manifestation of Severe Congenital Factor X Deficiency in a 20-Month-Old Male: Case Report and Review of the Literature.

Factor X deficiency (FXD) is a rare bleeding disorder, which can result in severe bleeding symptoms such as intracranial hemorrhage (ICH). The most common bleeding symptoms are epistaxis and gum bleeding. ICH is reported in 9-26% of all patients with FXD, mostly during the first month of life. Here, we present a rare case of a male presenting with ICH at the age of 20 months as the first manifestation of FXD. Secondary prophylaxis with factor X substitution once weekly prevented further bleeding.

Pharmacokinetics of a high-purity plasma-derived factor X concentrate in subjects with moderate or severe hereditary factor X deficiency.

INTRODUCTION: Hereditary factor X (FX) deficiency affects 1:500 000 to 1:1 000 000 of individuals. There are few published data on the pharmacokinetics (PK) of FX for existing treatments for FX deficiency, and no specific replacement factor concentrate exists. A high-purity plasma-derived FX concentrate (pdFX) has been developed for use as replacement therapy in subjects with hereditary FX deficiency. AIM: This analysis assessed pdFX PK after a single 25 IU kg(-1) bolus dose in subjects with hereditary moderate or severe FX deficiency (plasma FX activity [FX:C] <5 IU dL(-1) ). METHODS: For a baseline PK assessment, blood samples were taken predose and at intervals up to 144 h (7 days) post dose. After ≥6 months of on-demand pdFX treatment and treatment of ≥1 bleed with pdFX, subjects underwent repeat PK assessment. Samples were assayed for plasma FX:C (measured using the clotting and chromogenic assays) and FX antigen. RESULTS: FX:C peaked at 0.4-0.5 h and subsequently declined over the course of 144 h with a biphasic decay curve. PK parameters observed at the baseline (n = 16) and repeat (n = 15) assessments were equivalent, therefore summary PK values were obtained by combining data from both visits (n = 31). The mean terminal half-life and incremental recovery of pdFX was 29.4 h and 2.00 IU dL(-1) per IU kg(-1) respectively. CONCLUSION: This is the most comprehensive PK study to date in subjects with hereditary FX deficiency. These results are consistent with the observed haemostatic efficacy of pdFX and provide the PK data required for the treatment of hereditary FX deficiency using pdFX replacement therapy.

Cryptic 13q34 and 4q35.2 Deletions in an Italian Family.

Variations of DNA sequences in the human genome range from large, microscopically visible chromosome anomalies to single nucleotide changes. Submicroscopic genomic copy number variations, i.e. chromosomal imbalances which are undetectable by conventional cytogenetic analysis, play an intriguing clinical role. In this study, we describe the clinical consequences of the concurrent presence of an interstitial deletion in 13q34 and a terminal deletion in 4q35.2 in an Italian family. The index patient, a 19-year-old male, as well as his 12-year-old sister are carriers of both deletions, one of maternal and the other of paternal origin. The phenotype includes language delay, multiorgan involvement and bleeding diathesis with mild deficiency of factors X and VII. In the sister, the concomitant presence of Noonan syndrome may partly explain the clinical symptoms. The deleted region on chromosome 13 involves several genes (ATP11A, MCF2L, F7, F10, PROZ, PCID2, CUL4A, and LAMP1); some of these seem to play a role in the proband's phenotype. The terminal deletion in 4q35.2 contains other OMIM genes (FRG1, FRG2 and DBET); moreover, the 4q region is reported as a susceptibility locus for Crohn's disease, diagnosed in the proband's father. To our knowledge, this is the first report of a family with these 2 submicroscopic copy number changes. We tried to relate the clinical phenotype of the proband and his family to the molecular function of the involved genes.

Phenotype and genotype report on homozygous and heterozygous patients with congenital factor X deficiency.

Factor X deficiency is a severe rare hemorrhagic condition inherited as an autosomal recessive trait. It is one of the most severe recessive inherited coagulation disorders. We analyzed the clinical manifestations, laboratory phenotype and genotype in 10 patients with severe Factor X deficiency and in their heterozygous relatives. The most frequent bleeding episodes were hematomas (70%) and gum bleeding (60%). Fifty percent of the homozygous patients required blood transfusion and one-third of heterozygotes required treatment after surgery or delivery. The genetic characterization revealed six different missense mutations, two of which were novel: p.Glu69Lys and p.Asp103His. Haplotype analysis, performed with intra- and extra- FX gene polymorphic markers in Indian, Iranian and Italian patients with the same mutations failed to establish identity by descent, despite the same Caucasian origin. In conclusion, factor X deficiency was confirmed to be one of the most serious among rare bleeding disorders and genetically heterogeneous in different populations.

Incontinentia pigmenti: tres nuevos casos que demuestran que no es sólo cosa de mujeres / Incontinentia pigmenti: three new cases that demostrate it is not only a matter of women

La incontinentia pigmenti es una genodermatosis infrecuente con carácter multisistémico que sigue un patrón de herencia dominante ligado a X, por lo que resulta letal en la mayoría de varones afectados intraútero y muestra gran variabilidad clínica cuando se expresa en mujeres. Recientemente se ha encontrado que las mutaciones del gen NEMO/IKK-g localizado en Xq28 causan la expresión de la enfermedad, siendo una única mutación la responsable de aproximadamente un 80 % de los casos. La incontinentia pigmenti interesa a varias especialidades médicas, aunque son la clínica cutánea y la historia familiar las que marcan el diagnóstico, ayudadas de los hallazgos histológicos. No obstante, la identificación reciente del gen responsable del fenotipo de la enfermedad permite la resolución de muchos casos dudosos mediante estudio genético. Presentamos a continuación tres nuevos casos de esta patología (dos mujeres y un varón) en diferentes estadios evolutivos, que muestran el amplio espectro clínico con el que esta patología puede llegar a nuestra consulta

Incontinentia pigmenti is a rare, dominantly X-linked genodermatosis characterized by multisystemic involvement that is lethal prenatally in the majority of affected males and shows great clinical variability when it is expressed in women. Recently it has been shown that mutations of the gene NEMO/IKK-g located in Xq28 cause the expression of the disease, being only one mutation responsible for approximately 80 % of the cases. The diagnosis of incontinentia pigmenti is performed based on clinical features and family history with the support of histological findings. Nevertheless, as the gene responsible for the phenotype of the disease has been identified, a genetic study may be employed for doubtful cases. We report three cases of this entity (two women and one man) in different clinical stages of development that show the broad clinical spectrum we may encounter in the clinic

Successful treatment of transient acquired factor X deficiency by plasmapheresis with concomitant intravenous immunoglobulin and steroid therapy.

Two patients with no history of previous bleeding diatheses presented with active bleeding from multiple body sites, declining hemoglobin levels, and markedly prolonged prothrombin times (PT) and activated partial thromboplastin times (aPTT) with incomplete correction on PT mix assays. Both patients demonstrated a severe deficiency of factor X (F.X) (<1%; reference range 60-150%). F.X levels and bleeding were refractory to multiple transfusions of fresh frozen plasma (FFP) in both patients. In contrast, daily therapeutic plasma exchange (PLEX) with concomitant administration of intravenous immunoglobulin (IV IgG) and steroids produced a rapid increase in F.X levels with cessation of bleeding, followed by stabilization and normalization of F.X levels and progressive correction of coagulation times. Neither patient has demonstrated a recurrence of the bleeding tendency following discontinuation of steroid therapy. These patients had transient acquired F.X deficiency, a rare coagulopathy, which can result in a lethal bleeding diathesis. An IgG inhibitor that selectively inhibited F.X activation in Russell's viper venom or tissue factor/F.VIIa assays was demonstrated in one patient's pretreatment plasma. Previous treatment of hemorrhage in transient acquired F.X deficiency has been prothrombin complex and/or activated clotting concentrates, which can be associated with transient hypercoagulable states. This is the first reported use of PLEX in transient acquired F.X deficiency. PLEX is safe, efficacious, and rapidly restores hemostasis in this rare acquired bleeding disorder.

Progressive systemic sclerosis with the nephrotic syndrome and acquired factor X deficiency.

A patient with progressive systemic sclerosis (PSS) involving skin, digit, esophagus, and lung developed the nephrotic syndrome and rapidly progressive renal insufficiency. Renal pathology revealed capillary collapse, cellular crescents, arteriolar hyaline deposition, and mesangial proliferation. On immunofluorescence IgM, C3, and fibrinogen were present in mesangium and capillary walls. Prebiopsy coagulation screening revealed a factor X deficiency which caused substantial prolongation of the partial thromboplastin time without an overt bleeding diathesis. The acquired factor X deficiency resolved after fresh frozen plasma and vitamin K administration, although some spontaneous improvement was noted. Nephrotic syndrome may occasionally be seen in the acute fulminant form of PSS and should not deter diagnosis of PSS.

Coagulopathy in amyloidosis: combined deficiency of factors IX and X.

Combined severe deficiencies of blood clotting factors IX and X were observed in 2 patients who suffered from systemic amyloidosis. This unique deficiency state was marked by refractoriness to Vitamin K as well as to transfusion therapy. Increased antithrombin activity was present in both individuals and corresponded in time to the emergence of a monoclonal IgG kappa light chain paraprotein in 1. Both patients demonstrated profound bleeding disorders. It is hypothesized that the Vitamin K dependent factors have special affinity for amyloid deposits due to an unusual amino acid (gamma-carboxyglutamic acid) present in these factors.