Exon 35 skipping of FBN1 caused by c.4336G>A mutation may lead to Marfan syndrome / 中华检验医学杂志

ABSTRACT

Objective:To investigate the genetic etiology of a Marfan syndrome pedigree, and the impact of c.4336G>A variant on the splicing process of FBN1 gene.Methods:The proband was admitted to the Department of Cardiovascular Surgery of Xijing Hospital due to thoracic aortic aneurysm and dissection in August 2019. Multiplex PCR and next generation sequencing technology were used to detect 15 genes associated with hereditary aortic diseases in the proband. Then the pathogenic sites were further verified by Sanger sequencing, and above examinations were also performed among the family members of the proband. The effect of the mutation on mRNA splicing was predicted by splicing prediction software. RNAs from peripheral blood cells of the proband and the healthy person were extracted, and the effect of the mutation on mRNA splicing was verified by reverse transcription PCR and Sanger sequencing. The pathogenicity was analyzed by the recommendations from the American College of Medical Genetics (ACMG).Results:The gene panel detected a missense mutation of FBN1 gene (c.4336G>A) in the proband. Sanger sequencing results were consistent with that of panel. Sanger sequencing results showed that 4 family members were carriers of the same variant, and 3 out of the 4 family members presented signs of thoracic aortic aneurysm and dissection. The dbscSNV_ada_score and dbscSNV_rf_score software predicted that this mutation would lead to the occurrence of abnormal splicing of mRNA. The skipping of exon 35 was verified in the subsequent examinations by reverse transcription PCR and Sanger sequencing. The variant was classified as"pathogenic"according to ACMG guideline.Conclusion:FBN1 c.4336G>A mutation can cause the skipping of exon 35, and this might be the genetic mechanistic of severe cardiovascular abnormalities observed in this Marfan syndrome pedigree.