A novel mutation in ext2 caused hereditary multiple exostoses through reducing the synthesis of heparan sulfate

Abstract Hereditary multiple exostoses (HME) is a rare skeletal disorder characterized by the formation of multiple benign cartilage-capped tumors, usually in the metaphyseal region of the long bones. Over 70% of HME cases arise from monoallelic mutations in either of the two genes encoding the heparan sulfate (HS) synthesis enzymes, ext1 and ext2. To identify more HME-associated mutations, genomic DNA from members of five independent consanguineous families with HME was sequenced with whole exome sequencing (WES). A novel heterozygous splice site mutation (c.1173+2T>A) in ext2 was detected in all three affected members of family V. Further study showed that the novel mutation caused exon 7 of ext2 mRNA to be skipped during splicing and caused a frameshift after the codon for Arg360, which results in the appearance of new 43 codons, followed by a termination codon. Although the resulting truncated protein was still localized to the Golgi, similar to the full-length EXT2, its HS synthesis activity decreased by 40%. In this study, a novel splice site mutation in ext2 was identified and suggested to be a pathogenic mutation of HME, which may expand the genetic etiology spectrum of HME and may be helpful for clinical genetic counseling and prenatal diagnosis.

Bibliographic Details

Main Authors:	Xian,Caixia, Zhu,Mingwei, Nong,Tianying, Li,Yiqiang, Xie,Xingmei, Li,Xia, Li,Jiangui, Li,Jingchun, Wu,Jianping, Shi,Weizhe, Wei,Ping, Xu,Hongwen, Tang,Ya-ping
Format:	Digital revista
Language:	English
Published:	Sociedade Brasileira de Genética 2021
Online Access:	http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572021000300112
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