A novel mutation in exon 2 of FGB caused by c.221G>T substitution, predicting the replacement of the native Arginine at position 74 with a Leucine (p.Arg74Leu ) in a proband from a Kurdish family with dysfibrinogenaemia and familial venous and arterial thrombosis.

Dysfibrinogenaemias may present in either congenital or acquired form and are disorders of fibrinogen structure which may or may not be associated with abnormal function. More than 100 point mutations with single amino acid substitutions have been identified in over 400 families. These lead to defective DNA in the translated fibrinogen molecule. Such cases have improved our understanding of the fibrinogen-fibrin structure. Six members of a consanguineous family including a female proband, a female sibling, three male siblings and a daughter, with ages between 29 years and 53 years presented with early onset venous and premature arterial thromboembolic disease were investigated for a pro-thrombotic tendency associated with dysfibrinogenaemia. The family was investigated using standard coagulation assays and DNA sequencing of the genes encoding the FGA, FGB and FGG. All cases have dysfibrinogenaemia with a fibrinogen level 1.4 to 1.5 (1.9-4.3 g/L). Thrombophilia testing (including AT, PS & PC, F5 G1691A (FV Leiden)/F2 (prothombin G20210A) genotypes, homocysteine, antiphosphlipid antibody, paroxysmal nocturnal haemoglobinuria by flow cytometry and Janus Kinase-2 (exon 14)) were normal. PCR amplification and sequencing of exon 2 of FBG revealed a heterozygous mutation for a c.221G> T substitution, predicting the replacement of the native Arginine at position 74 with a Leucine (p.Arg74Leu ). In silico analysis of p.Arg74Leu strongly support pathogenicity. A novel mutation was identified in exon 2 of FGB caused by c.221G> T substitution, predicting the replacement of Arginine at position 74 with a Leucine (p.Arg74Leu ) in a proband from a Kurdish family with dysfibrinogenaemia and familial venous and arterial thrombosis.