Identification of a novel mutation in the EXT1 gene from a patient with multiple osteochondromas by exome sequencing
Identification of a novel mutation in the EXT1 gene from a patient with multiple osteochondromas by exome sequencing
复制标题
通过外显子组测序鉴定多发性骨软骨瘤患者 EXT1 基因的新突变
DOI：
10.3892/mmr.2016.6086
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发表时间：
2017-02-01
影响因子：
3.4
通讯作者：
Hu, Xiao
中科院分区：
文献类型：
--
作者：
Hong, Guolin;Guo, Xiaoyan;Hu, Xiao
多发性骨软骨瘤（MO）是一种常染色体骨骼疾病，其发病机制尚不清楚。为了进一步阐明该病的遗传机制，我们对一个三代MO家系进行了观察和研究，并通过外显子组测序发现1例MO患者的exotosin 1（exotosin 1，EXT1）基因存在一个新的移码突变（c.335_336insA）。通过桑格测序和与200名无关健康对照的比较，进一步验证了这一点。免疫组化和多序列比对，以确定候选突变的致病性。多序列比对表明，EXT1基因的335和336密码子在脊椎动物中高度保守。免疫组化显示，与没有EXT1突变的MO患者相比，MO和这种突变患者的EXT1蛋白表达水平降低。由于c.335_336insA出现在EXT1的外显子1中，引入了提前终止密码子，导致截短的EXT1。因此，集成和功能性EXT 1被减少。EXT1参与硫酸乙酰肝素（HS）的生物合成，这是一种必需的分子，其功能障碍可能导致MO。本研究报道的EXT1基因c.335_336insA突变扩大了MO的致病突变谱，可能有助于MO的遗传咨询和产前诊断。
Multiple osteochondromas (MO) is an autosomal skeletal disease with an elusive molecular mechanism. To further elucidate the genetic mechanism of the disease a three-generation Chinese family with MO was observed and researched, and a novel frameshift mutation (c.335_336insA) in the exotosin 1 (EXT1) gene of one patient with MO was observed through exome sequencing. This was further validated by Sanger sequencing and comparison with 200 unrelated healthy controls. Immunohistochemistry and multiple sequence alignment were performed to determine the pathogenicity of the candidate mutation. Multiple sequence alignment suggested that codon 335 and 336 in the EXT1 gene were highly conserved regions in vertebrates. Immunohistochemistry revealed that EXT1 protein expression levels were decreased in a patient with MO and this mutation compared with a patient with MO who had no EXT1 mutation. Owing to the appearance of c.335_336insA in exon 1 of EXT1, a premature stop codon was introduced, resulting in truncated EXT1. As a result integrated and functional EXT1 was reduced. EXT1 is involved in the biosynthesis of heparan sulfate (HS), an essential molecule, and its dysfunction may lead to MO. The novel mutation of c.335_336insA in the EXT1 gene reported in the present study has enlarged the causal mutation spectrum of MO, and may assist genetic counseling and prenatal diagnosis of MO.