[Analysis of genetic variants and molecular pathogenesis in a Chinese pedigree affected with Multiple epiphyseal dysplasia].

Objective: To analyze the genetic variant and molecular pathogenesis in a Chinese pedigree affected with Multiple epiphyseal dysplasia (MED).

Methods: A MED pedigree which had presented at the Beijing Jishuitan Hospital Affiliated to Capital Medical University on September 13, 2020 was selected as the study subject. Clinical data of the pedigree were collected. Peripheral blood samples were drawn from pedigree members for the extraction of genomic DNA. Whole exome sequencing (WES) was carried out for the pedigree. Candidate variant was verified by Sanger sequencing. Wild type and mutant SLC26A2 expression plasmids were constructed and transfected into human primary chondrocytes. The effect of the variants on the protein localization and cell proliferation was determined by immunofluorescence and CCK8 assays.

Results: WES and Sanger sequencing revealed that the proband has harbored compound heterozygous variants of the SLC26A2 gene, including a paternally derived c.484G>T (p.Val162Leu) missense variant and a maternally derived c.485_486delTG (p.Val162Glyfs*12) frameshifting variant. The SLC26A2WT and its mutant SLC26A2Val162Leu and SLC26A2Val162Glyfs*12 expression plasmids were distributed in the nuclei and cytoplasm of human primary chondrocytes. Compared with SLC26A2WT, the expressions of SLC26A2Val162Leu and SLC26A2Val162Glyfs*12 were decreased, along with reduced proliferation of human primary chondrocytes.

Conclusion: The c.484G>T and c.485_486delTG compound heterozygous variants of the SLC26A2 gene may affect the proliferation of human primary chondrocytes and underlay the pathogenesis of MED in this pedigree.