[Analysis of VWF Gene c.7332G>A Nonsense Mutation Pedigree and Study of Molecular Pathogenesis]

To analyze the genetic characteristics of the VWF gene c. 7332G>A nonsense mutation and explore its molecular pathogenesis.

Phenotypic diagnosis of the proband was performed using VWF:Ag, VWF:RCo, FⅧ:C and multimeric analysis. The probands were genotyped by NGS whole-exome sequencing, and the sequencing results were validated by sanger sequencing. The family members were genotyped by Sanger sequencing. The VWF gene c. 7332G>A nonsense mutant plasmid was constructed. After transfection, the function of VWF gene c. 7332G>A mutant plasmid was verified at cell level in vitro. The mRNA level was detected by qRT-PCR, and the expression level of protein was detected by Western blot, the function of multimerization was verified by the multimeric analysis.

VWF:Ag and VWF:RCo were all less than 3% in the proband, and the multimeric analysis showed multimer deficiency. The proband was diagnosed as type 3 VWD. The homozygous nonsense mutation of VWF gene c.7332G>A was detected by gene sequencing. The VWF mRNA level of the mutant plasmid was decreased, and the VWF protein expression in the cell supernatant was decreased, the mutant protein was truncated and the function of VWF multimerization was impaired.

A homozygous mutation in exon 43 of VWF gene, c.7332G>A, was responsible for the probands type 3 VWD in the proband. The mutation caused a decrease in the relative level of VWF mRNA and protein, and impaired the function of VWF multimerization.