[A novel splicing acceptor variant of the FBN2 gene contributes to a case of congenital contractural arachnodactyly].

OBJECTIVE

To identify the pathogenic variants from a patient with suspected congenital contractural arachnodactyly, and to explore the possible molecular genetic pathogenesis, so as to provide evidence for clinical diagnosis.

METHODS

Whole exome sequencing was performed for the patient. The splicing site variation of candidate pathogenic genes was verified by Sanger sequencing, and the new transcript sequence was determined by RT-PCR and TA-cloning sequencing.

RESULTS

The patient carried a heterozygous c.533-1G>C variant of FBN2 gene, which was not reported. The sequencing of mRNA showed that the variant leaded to the disappearance of the canonical splice acceptor site of FBN2 gene and the activation of a cryptic splice acceptor site at c.533-71, resulting in the insertion of 70 bp sequence in the new transcript. It was speculated that the polypeptide encoded by the new transcript changed from valine (Val) to serine (Ser) at amino acid 179, and prematurely terminated after 26 aminoacids. According to the guidelines of American College of Medical Genetics and Genomics, the variant of FBN2 gene c. 533-1G>C was determined as pathogenic (PVS1+PM2+PP3 ).

CONCLUSION

A novel splicing variant of FBN2 gene (c.533-1G>C) was identified, which can lead to congenital contractural arachnodactyly.