Sankaranarayanan Rajkumar, Vidya Nair Gopinathan, Vasavada Abhay Raghukant
a Department of Molecular Genetics and Biochemistry , Iladevi Cataract and IOL Research Centre , Ahmedabad , India.
b Department of Genetics , Aditya Jyot Foundation for Twinkling Little Eyes , Mumbai , India.
Ophthalmic Genet. 2019 Apr;40(2):99-109. doi: 10.1080/13816810.2019.1582068. Epub 2019 Mar 14.
Age-related cataract (ARC) is profoundly associated with oxidative stress. Iron plays a pivotal role in generating oxidative stress and promoting deleterious irreversible damage to the macromolecules. Divalent metal transporter 1 (DMT1) mediates the uptake of iron into the cell. Aberrant transcript expression of DMT1 gene in lenses of human ARC was reported. The present investigated the genetic association between DMT1 gene polymorphisms and risk of ARC.
DNA from peripheral blood of ARC subjects (n = 764) and age-matched controls (n = 794) was isolated. Genotyping of three single-nucleotide polymorphisms (SNPs) - rs224589 (C/A), rs1048230 (T/C), and rs2285230 (T/C) - of DMT1 gene was performed by polymerase chain reaction (PCR)-restriction fragment length polymorphism technique. Level of DMT1 transcript expression was determined by quantitative real-time PCR analysis using RNA from lens epithelial and fiber cells.
Nuclear cataract showed a higher frequency of CC genotypes (OR = 1.40; 95%CI = 1.01-1.95; p = 0.04) of SNP rs224589 and a significantly lower frequency of A-T-T haplotype (OR = 0.63; 95%CI = 0.42-0.92; p = 0.02) than that of controls. The A-T-T haplotype demonstrated a dominant protective effect against disease risk when compared to the more common haplotype (C-T-T) (p = 0.01). The haplotype pairs C-T-T/C-T-T and A-C-C/A-C-C showed higher level of transcript expression of DMT1 than C-T-T/A-T-T haplotype pair (p < 0.05). Further, a novel genetic variation (c.1328A>G; p.N443S) in exon 3 of DMT1 gene was observed in a subject with nuclear cataract.
The results highlighted a protective association of A-T-T haplotype against the risk of ARC.
年龄相关性白内障（ARC）与氧化应激密切相关。铁在产生氧化应激以及促进对大分子的有害不可逆损伤中起关键作用。二价金属转运蛋白1（DMT1）介导铁进入细胞。有报道称人类ARC晶状体中DMT1基因的转录本表达异常。本研究调查了DMT1基因多态性与ARC风险之间的遗传关联。
从ARC患者（n = 764）和年龄匹配的对照组（n = 794）的外周血中分离DNA。采用聚合酶链反应（PCR）-限制性片段长度多态性技术对DMT1基因的三个单核苷酸多态性（SNP）——rs224589（C/A）、rs1048230（T/C）和rs2285230（T/C）进行基因分型。使用晶状体上皮细胞和纤维细胞的RNA，通过定量实时PCR分析确定DMT1转录本表达水平。
核性白内障患者中，SNP rs224589的CC基因型频率较高（OR = 1.40；95%CI = 1.01 - 1.95；p = 0.04），A-T-T单倍型频率显著低于对照组（OR = 0.63；95%CI = 0.42 - 0.92；p = 0.02）。与更常见的单倍型（C-T-T）相比，A-T-T单倍型对疾病风险具有显著的保护作用（p = 0.01）。单倍型对C-T-T/C-T-T和A-C-C/A-C-C的DMT1转录本表达水平高于C-T-T/A-T-T单倍型对（p < 0.05）。此外，在一名核性白内障患者中观察到DMT1基因外显子3中的一个新的基因变异（c.1328A>G；p.N443S）。
结果突出了A-T-T单倍型对ARC风险的保护关联。
