Hypodysfibrinogenaemia due to production of mutant fibrinogen alpha-chains lacking fibrinopeptide A and polymerisation knob 'A'.
Inherited disorders of fibrinogen are rare and affect either the quantity (hypofibrinogenaemia and afibrinogenaemia) or the quality of the circulating fibrinogen (dysfibrinogenaemia) or both (hypodysfibrinogenaemia). Extensive allelic heterogeneity has been found for all these disorders: in congenital afibrinogenaemia for example more than 40 mutations, the majority in FGA , have been identified in homozygosity or in compound heterozygosity. Numerous mutations have also been identified in patients with hypofibrinogenaemia, many of these patients are in fact heterozygous carriers of afibrinogenaemia mutations. Despite the number of genetic analyses performed, the study of additional patients still allows the identification of novel mutations. Here we describe the characterization of a novel FGA intron 2 donor splice-site mutation (Fibrinogen Montpellier II) identified in three siblings with hypodysfibrinogenaemia. Functional analysis of RNA produced by the mutant minigene in COS-7 cells revealed that the mutation led to the in-frame skipping of exon 2. Western blot analysis of COS-7 cells expressing an exon 2 deleted FGA cDNA revealed that an alpha-chain lacking exon 2, which codes in particular for fibrinopeptide A and polymerisation knob 'A', has the potential to be assembled into a hexamer and secreted. Analysis of precipitated fibrinogen from patient plasma showed that the defect leads to the presence in the circulation of alpha-chains lacking knob 'A' which is essential for the early stages of fibrin polymerisation. Fibrin made from purified patient fibrinogen clotted with thrombin displayed thinner fibers with frequent ends and large pores.
Vorjohann
Silja
S
Department of Genetic Medicine and Development, University of Geneva Medical Centre, Geneva, Switzerland. Marguerite.Neerman-Arbez@unige.ch
Fish
Richard J
RJ
Biron-Andréani
Christine
C
Nagaswami
Chandrasekaran
C
Weisel
John W
JW
Boulot
Pierre
P
Reyftmann
Lionel
L
de Moerloose
Philippe
P
Neerman-Arbez
Marguerite
M
D000293:Adolescent; D000328:Adult; D000347:Afibrinogenemia / Q000097:blood / Q000235:genetics*; D000818:Animals; D001777:Blood Coagulation / Q000235:genetics*; D001780:Blood Coagulation Tests; D015153:Blotting, Western; D019556:COS Cells; D002522:Chlorocebus aethiops; D004252:DNA Mutational Analysis; D005260:Female; D005340:Fibrinogen / Q000235:genetics* / Q000378:metabolism; D015241:Fibrinogens, Abnormal / Q000235:genetics* / Q000378:metabolism; D005344:Fibrinopeptide A / Q000235:genetics* / Q000378:metabolism; D020022:Genetic Predisposition to Disease; D006579:Heterozygote; D006801:Humans; D007438:Introns; D008297:Male; D008855:Microscopy, Electron, Scanning; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D055503:Protein Multimerization; D012326:RNA Splicing; D014162:Transfection; D055815:Young Adult
D015241:Fibrinogens, Abnormal; C464794:fibrinogen Aalpha; D005344:Fibrinopeptide A; D005340:Fibrinogen
Nature. 1968 Apr 13;218(5137):134-7
5645286
Biophys J. 1992 Jul;63(1):111-28
1420861
Nature. 1978 Oct 12;275(5680):501-5
692730
Gene. 1989 Apr 15;77(1):51-9
2744487
Adv Protein Chem. 2005;70:247-99
15837518
J Mol Evol. 1997 Jul;45(1):50-9
9211734
Semin Thromb Hemost. 1993;19(4):386-95
8140431
Cell Mol Life Sci. 2004 Jun;61(12):1427-38
15197468
J Biol Chem. 1996 May 24;271(21):12674-80
8647881
Ann N Y Acad Sci. 2001;936:89-90
11460527
J Thromb Haemost. 2007 Dec;5(12):2352-9
17922804
J Thromb Haemost. 2006 Oct;4(10):2115-29
16999847
J Thromb Haemost. 2007 Dec;5(12):2344-51
17892530
Blood. 2004 Dec 1;104(12):3618-23
15284111
Nat Protoc. 2007;2(4):953-71
17446895
Hum Mutat. 2007 Jun;28(6):540-53
17295221
Thromb Haemost. 2010 Feb;103(2):478-9
20126833
Br J Haematol. 2007 Jul;138(1):117-24
17555455
J Med Genet. 2005 Sep;42(9):e57
16141000
Ann N Y Acad Sci. 2001;936:11-30
11460466
Proc Natl Acad Sci U S A. 1985 Apr;82(8):2344-8
2986113
Blood. 1985 Sep;66(3):503-7
4040783
J Biol Chem. 1985 Apr 10;260(7):4390-6
3156856
Thromb Haemost. 1995 Jan;73(1):151-61
7740487
Blood. 2000 Jul 1;96(1):149-52
10891444
J Clin Invest. 1995 Dec;96(6):2854-8
8675656
Blood. 2007 Jan 1;109(1):130-8
16940416
Ann N Y Acad Sci. 2001;936:480-95
11460506
Stain Technol. 1983 Nov;58(6):347-51
6679126