Coagulation factor XI: a database of mutations and polymorphisms associated with factor XI deficiency

Genetic analysis of a pedigree with combined factor XII and factor XI deficiency

The objective of the present study was to identify the gene mutations of factor XI (FXI) and factor XII (FXII) in a Chinese pedigree with combined congenital FXI and FXII deficiencies. The proband was a 40-year-old woman with deficiency in both FXI (49%) and FXII (0%) activities. Blood samples from 10 other members of her family were collected and used for detection of FXI, FXII activities (FXI: C, FXII: C) and antigen levels. Genetic analysis to detect mutations in FXI, FXII genes was also performed. The proband's mother, three brothers, two sisters, her son and her daughter all have lowered FXII: C. Furthermore, her mother and one of her brothers also have lowered FXI: C. Gene sequencing for FXI in affected members revealed a heterozygous C23179T point mutation in exon 11 resulting in substitution of arginine 396 by cysteine. Gene sequencing for FXII revealed a C46T in the promoter region and a deletion mutation of two nucleotides CA at position 9160 and 9161 in exon 5. The deletion mutation can lead to frameshift mutation and premature termination of transcription in exon 6. We found a new heterozygous missense mutation in the FXI gene and a new nonsense mutation of two nucleotides deletion which caused frameshift mutation and premature termination of transcription in the FXII gene in a Chinese family with combined FXI and FXII deficiencies.

Molecular characterization of in-frame and out-of-frame alternative splicings in coagulation factor XI pre-mRNA

Alternative splicing of pre-mRNAs is a central process to the generation of proteome complexity. However, many alternative mRNA isoforms carry premature termination codons (PTCs) rendering them possible targets for the nonsense-mediated mRNA decay (NMD) pathway. The F11 gene consists of 15 exons spanning approximately 23 kb on chromosome 4q35 and codes for coagulation factor XI (FXI), a 160-kDa dimeric zymogen composed of 4 apple domains and a serine protease domain. Here, we characterized the F11 splicing pattern in human liver and platelets identifying multiple in-frame and out-of-frame splicing events. Inhibition of NMD resulted in the up-regulation of all unproductively spliced F11 transcripts, thus providing evidence that these PTC-containing mRNAs are under the control of NMD. Among in-frame alternatively spliced transcripts, the one skipping exons 6 and 7 would lead to the synthesis of a FXI protein lacking 1 apple domain (FXI-Δ6/7). Ex vivo expression in mammalian cells demonstrated that FXI-Δ6/7 is mostly retained intracellularly, and secreted only in low amounts. Traces of this FXI isoform were detectable in human plasma. Our results suggest that the coupling of alternative splicing and NMD may play a role in regulating F11 expression, and point to the existence of a novel FXI isoform.

First diagnosis of factor XI deficiency in a patient with subarachnoid haemorrhage

Aneurismal subarachnoid haemorrhage (SAH) is a devastating event affecting patients at a fairly young age and accounting for significant morbidity and mortality. Although there is progress concerning diagnostic methods and treatment, this case report might add interesting data to the current understanding of this disease and its clinical management with respect to circumstantial deficiency of the coagulation factor XI (FXI). In this report, we present a unique case of aneurismal SAH in a patient with underlying coagulation FXI deficiency which was incidentally identified after patient's admission, as routine blood tests revealed increased activated partial thromboplastin time. Despite early successful treatment with coiling, the patient had a second episode of SAH a few months after his discharge, due to aneurysm revascularization and rupture. Molecular analysis and identification of new mutations were performed. We describe management of SAH with respect to a coexisting bleeding disorder; also testing of patient's family members for FXI deficiency and decisions about screening for intracranial aneurysm are described. Late complications of SAH are - among others - aneurysm revascularization and rebleeding. Although FXI deficiency could be considered an exacerbating factor, it cannot be definitely implicated.

Update on the physiology and pathology of factor IX activation by factor XIa

Factor IX is a key component of the plasma system that forms a fibrin clot at a site of vascular injury. Activation of factor IX by factor XIa is required in certain situations to prevent bleeding from premature clot degradation. Factor XIa is a coagulation protease comprised of two identical subunits. The biochemical and physiologic implications of this unusual structural feature are being actively investigated. Congenital factor XI deficiency causes a mild-to-moderate bleeding disorder, with hemorrhage typically involving the oral/nasal cavities and the urinary tract. Current treatment recommendations take this tissue-specific bleeding pattern into account and target factor replacement to certain types of procedures and clinical situations. Results from animal models and human population studies indicate that factor XI contributes to thromboembolic disease. This protease may therefore be a legitimate therapeutic target.

A novel mutation (Gln433Glu) in exon 12 combined with the G insertion in exon 13 causes severe factor XI deficiency in Japanese patients

Factor XI (FXI) deficiency is an autosomal, incompletely recessive coagulopathy. This disorder is rare in the general population worldwide, but is one of the most common inherited diseases in Ashkenazi Jews. It has been reported that a significantly higher frequency of allelic heterogeneity occurs in different ethnic groups. The study objective was to study the molecular basis of this disease in a Japanese family. Two Japanese brothers with severe FXI deficiency and three other family members were screened by direct sequencing analysis after polymerase chain reaction. We identified a novel mutation, a C-to-G transition at position 1394 in exon 12 in the FXI gene (F11 c.1394 C>G). This transition resulted in a missense mutation (Gln433Glu), which led to the disruption of the catalytic domain structure of the FXI molecule. This change, combined with a G insertion in exon 13 (501/502 ins G), led to a frameshift mutation, which has previously been reported in only one other Japanese patient. In conclusion, the compound heterozygous novel mutations that cause severe FXI deficiency were found in Japanese patients.

Identification of five novel mutations in the factor XI gene (F11) of patients with factor XI deficiency

Factor XI (FXI) deficiency is an inherited autosomal recessive disorder associated with bleeding of variable severity. However, many cases of dominant disease transmission have been recently described. This disorder is rare in the general population, whereas it is commonly found in individuals of Ashkenazi Jewish ancestry. This study reports the molecular genetic analysis of FXI deficiencies in 11 unrelated families of different origin. Five novel mutations have been identified. Severe FXI deficiency of two unrelated patients resulted from two novel mutations: one deletion (960-961delGT) in exon 9 predicting a frameshift, and a Ser-4Leu mutation located in the signal peptide. In addition, three novel missense mutations associated with partial FXI deficiency have been identified: Cys122Tyr, Glu297Lys and Glu579Lys.