ABSTRACT

Purpose

To identify the mutation causing an autosomal dominant congenital nuclear cataract in a south Indian family by whole exome sequencing and to characterize further phenotypically the same in a zebra fish model.

Methods

A six-generation family (DKEC1) with several affected members registered at the Regional Institute of Ophthalmology (RIO), Chennai was documented to have congenital nuclear cataract. Detailed clinical history and blood samples were collected from all available family members. Genomic DNA of the proband was subjected to whole exome sequencing. Sequence variations suggestive of putative mutations were further confirmed by bidirectional sequencing and restriction site analysis. Functional analysis of the mutant CRYGC E128* in zebrafish embryos was done to dissect out the pathogenicity.

Results

A unique variation viz., c.382 G > T in the coding region of the CRYGC gene, resulting in a premature stop codon at position 128 (E128*) was documented in the affected family members. The same was absent in unaffected family members and in 120 unrelated population controls checked. Bioinformatic tools predicted that the mutation might cause a deleterious effect on protein structure and function. Molecular function analysis of this novel mutation (p. E128*, CRYGC) in the zebrafish indicated this mutation to impair lens transparency.

Conclusion

This study identified a novel CRYGC mutation, E128* to cause autosomal dominant congenital nuclear cataract in a large south Indian family. Our study provides a new insight onto how the mutation might affect the γC-crystallin structure and function besides emphasizing the need for genetic diagnosis toward vision restoration.

中文翻译：

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一种新的CRYGC E128 *突变，位于南印度种人的常染色体显性遗传性白内障基础上。

摘要

目的

通过全外显子组测序鉴定导致印度南部家庭常染色体显性遗传性先天性白内障的突变，并进一步表征斑马鱼模型的表型相同。

方法

钦奈地区有一个六代家庭（DKEC1），有几个受影响的成员在地区眼科研究所（RIO）注册。从所有可用的家庭成员中收集详细的临床病史和血液样本。先证者的基因组DNA经历了完整的外显子组测序。双向测序和限制性酶切位点分析进一步证实了提示推定突变的序列变异。对斑马鱼胚胎中的突变CRYGC E128 *进行功能分析，以剖析其致病性。

结果

在受影响的家庭成员中记录了CRYGC基因编码区的一个独特变异，即c.382 G> T ，导致在128位的早期终止密码子（E128 *）。在未受影响的家庭成员和120个无亲缘关系的人口控制中也没有这种情况。生物信息学工具预测该突变可能对蛋白质的结构和功能产生有害影响。斑马鱼中这种新突变（p128 E128 *，CRYGC）的分子功能分析表明，这种突变会损害晶状体的透明度。

结论

这项研究确定了一个新的CRYGC突变E128 *，该突变在一个印度南部大家庭中引起常染色体显性遗传性先天性白内障。我们的研究为该突变可能如何影响γC-晶状体蛋白的结构和功能提供了新的见识，同时强调了对视力恢复进行遗传诊断的需要。