Congenital factor XII (FXII) deficiency is a rare autosomal recessive disorder, characterized by a great variability in its clinical manifestations. In this study, we screened for mutations in the F12 gene of 4 unrelated patients with FXII coagulant activity <10% of that of normal human plasma. To investigate the molecular defects in these FXII-deficient patients, we performed FXII mutation screening. By sequencing all coding exons as well as flanking intronic regions of the F12 gene, 6 different mutations, including 3 missense mutations (Gly341Arg, Glu502Lys and Gly542 Ser), 1 insertion (7142insertC) and 2 deletions (5741-5742 delCA and 6753-6755delACA), were identified on the F12 gene. Three of them (Gly341Arg, 5741-5742delCA and 6753-6755delACA) are reported here for the first time. Computer-based algorithms predicted these missense mutations to be deleterious. This study has increased our knowledge of the mutational spectrum underlying FXII deficiency.

ABSTRACT. We investigated the alteration of coagulation state in a protein C (PC) deficiency pedigree and the impact of the PC gene mutations. The pedigree of a proband with cerebral hemorrhagic infarction had sixteen members with four generations. The plasma levels of PC activity (PC:A), protein S activity (PS:A), factor V:C and factor VIII:C, and routine coagulation tests were measured. Nine exons of the PC gene (PROC) were sequenced. Plasma PC:A and PC antigen (PC:Ag) of the proband were 26 and 18%, respectively, which was significantly lower than normal ranges. Two heterozygous missense mutations of PC in the proband were identified, T>G at site 6128 (exon 7) and G>C at site 8478 (exon 9) resulting in F139V and D255H, respectively. The family members with F139V (N = 4) or D255H (N = 4) had lower levels of PC:A and PC:Ag than members with wild-type 2970

Congenital hypofibrinogenemia is a rare disorder caused by heterozygous mutations in the fibrinogen genes. The aim of this study was to elucidate the molecular defects in two unrelated families with hypofibrinogenemia. The proband from family A was a 19-year-old Chinese boy who was suffering from cervical lymphadenitis. A low plasma fibrinogen concentration (0.63 g/l by Clauss method and 0.77 g/l by immunoturbidimetry) was found in routine clotting tests. Further gene analysis revealed a heterozygous g.5792 G>T mutation in exon 7 of the FGG, leading to a novel Trp208Leu change in the γ D domain. This mutation was also found in other family members with low fibrinogen levels. The proposita from family B was a 37-year-old female who suffered from recurrent shoulder pain for 7 years. Routine clotting studies revealed that her prothrombin time was 15.5 s (normal range: 11.8-14.8 s) and thrombin time was 22.8 s (normal range: 14.0-20.0 s), and the fibrinogen concentration in her plasma was only 0.64 g/l by Clauss method and 0.79 g/l by immunoturbidimetry. A heterozygous A>C transition at nucleotide 5864 of FGG was found in the γ chain, causing a Lys232Thr substitution in the fibrinogen. Further sequencing established that her mother, son, brother and nephew were also heterozygous for the mutation.

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To explore the phenotype and genotype of a Chinese family with hereditary factor V deficiency. Routine blood coagulation indexes were detected by one-stage clotting method, whereas factor V antigen was detected by ELISA. All exons and intron–exon boundaries of F5 gene were amplified by PCR and sequenced directly. The suspected mutation was confirmed by reverse sequencing. Bioinformatics softwares were used to analyze the possible impact of this mutation. Phenotypic analysis showed that the proband had significantly prolonged prothrombin time and activated partial thromboplastin time, and his factor V clotting activity was decreased to 3%. Genetic analysis revealed a homozygous missense mutation c.5227G>A (p.Gly1715Ser) in exon 16 of F5 gene. Bioinformatics and structural analysis demonstrated this mutation was deleterious and could affect the integrity of local intermolecular structures. The missense mutation (Gly1715Ser) was responsible for the decrease of factor V clotting activity and factor V antigen in this family, and caused type I hereditary factor V deficiency.