[Genetic analysis of a Chinese pedigree affected with Congenital dysfibrinogenemia due to variant of FGG gene].

OBJECTIVE: To explore the coagulation deficit and genetic basis for a Chinese pedigree affected with Congenital dysfibrinogenemia (CD). METHODS: Peripheral venous blood samples of the proband and her family members (including 4 individuals from three generations) were subjected to routine blood test and assays of liver and kidney functions and viral hepatitis to exclude related diseases. Clauss method and DFg-PT method were used to determine the fibrinogen activity (Fg:C), and an immunoturbidimetric assay was used to determine the level of fibrinogen antigen (Fg:Ag). All of the exons (22 in total) and their flanking sequences of the FGA, FGB and FGG genes were amplified by PCR and directly sequenced. Variants in the coding regions of the three genes and transcriptional splicing sites were screened by using Mutation SurveyorTM software. RESULTS: The Clauss method showed that Fg:C was significantly reduced in the proband and her father, whilst her mother and son were normal. With the DFg-PT method, the proband, her parents and son were all within the normal range. The Fg:C/Fg:Ag ratio of the proband and her father was lower than 0.7, whilst her mother and son were above 0.7. No significant change in the prothrombin time, activated partial thromboplastin clotting time and thrombin time was noted. Two genetic variants were detected, which included a homozygous missense variant in the FGA gene [c.991A>G (p.Thr331Ala)], which was predicted to be benign, and a heterozygous missense variant of the γ chain of the FGG gene [c.1211C>G (p.Ser404Phe)], which is located in a conserved region and unreported in the CLINVAR/HGMD/EXAC/1000G databases and literature. CONCLUSION: This pedigree has conformed to the autosomal dominant inheritance of CD. The c.1211C>T (p.Ser404Phe) missense variant of the γ chain of the FGG gene probably underlay the pathogenesis of CD in this pedigree. The variant was unreported previously and named as "Fibrinogen Harbin II Ser404Phe".

[Clinical and molecular-biological study of a May-Hegglin anomaly family].

OBJECTIVE: To study the changes of platelet in May-Hegglin anomaly (MHA) and the molecular pathogenesis mechanism. METHODS: Peripheral blood was drawn from the MHA proband, her father and her uncle. Platelet count and morphology were examined by automatic blood cell counter and microscopy, respectively. The platelet membrane protein was examined by flow cytometry. Membrane antibodies were determined by ELISA. PCR was used to amplify the exons 25, 31 approximately 32, 38 and 40 of the MYH 9 gene in the MHA patient and her diseased father. Furthermore, PCR products were sequenced, a specific point mutation was identified and inclusions (Dohle's body) in the neutrophil was detected by indirect immunofluorescence technique. RESULTS: It was proved that in MHA patients, platelet count was higher by cell counter than by microscope (P < 0.01). Giant platelet was 94% but platelet membrane proteins (CD41, CD61, CD42A, CD42b) were in normal range. Membrane antibodies was undetectable. An A5521G mutation (GAG-->AAG) in the exon 38 was found in the proband and her diseased father, resulting in a characteristic change of NMMHC-A1841 (Glutamic acid-->Arginine), which was not found in other members of the family and in normal controls. Spindle-like inclusions with fluorescence were clearly displayed in neutrophil cytoplasm. CONCLUSION: The molecular pathogenesis mechanism of May-Hegglin anomaly is the mutation in MYH 9 gene.