Chung Doug D, Frausto Ricardo F, Cervantes Aleck E, Gee Katherine M, Zakharevich Marina, Hanser Evelyn M, Stone Edwin M, Heon Elise, Aldave Anthony J
Stein Eye Institute, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, California, United States of America.
Department of Ophthalmology, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America.
PLoS One. 2017 Jan 3;12(1):e0169215. doi: 10.1371/journal.pone.0169215. eCollection 2017.
To identify the genetic basis of posterior polymorphous corneal dystrophy (PPCD) in families mapped to the PPCD1 locus and in affected individuals without ZEB1 coding region mutations.
The promoter, 5' UTR, and coding regions of OVOL2 was screened in the PPCD family in which linkage analysis established the PPCD1 locus and in 26 PPCD probands who did not harbor a ZEB1 mutation. Copy number variation (CNV) analysis in the PPCD1 and PPCD3 intervals was performed on DNA samples from eight probands using aCGH. Luciferase reporter assays were performed in human corneal endothelial cells to determine the impact of the identified potentially pathogenic variants on OVOL2 promoter activity.
OVOL2 mutation analysis in the first PPCD1-linked family demonstrated segregation of the c.-307T>C variant with the affected phenotype. In the other 26 probands screened, one heterozygous coding region variant and five promoter region heterozygous variants were identified, though none are likely pathogenic based on allele frequency. Array CGH in the PPCD1 and PPCD3 loci excluded the presence of CNV involving either OVOL2 or ZEB1, respectively. The c.-307T>C variant demonstrated increased promoter activity in corneal endothelial cells when compared to the wild-type sequence as has been demonstrated previously in another cell type.
Previously identified as the cause of PPCD1, the OVOL2 promoter variant c.-307T>C was herein identified in the original family that established the PPCD1 locus. However, the failure to identify presumed pathogenic coding or non-coding OVOL2 or ZEB1 variants, or CNV involving the PPCD1 and PPCD3 loci in 26 other PPCD probands suggests that other genetic loci may be involved in the pathogenesis of PPCD.
确定定位到PPCD1位点的家族性及无ZEB1编码区突变的后极性多形性角膜营养不良（PPCD）患者的遗传基础。
对通过连锁分析确定为PPCD1位点的PPCD家族以及26例未携带ZEB1突变的PPCD先证者，筛查OVOL2的启动子、5'非翻译区（UTR）和编码区。使用比较基因组杂交（aCGH）对8例先证者的DNA样本进行PPCD1和PPCD3区间的拷贝数变异（CNV）分析。在人角膜内皮细胞中进行荧光素酶报告基因检测，以确定所鉴定的潜在致病变异对OVOL2启动子活性的影响。
在首个与PPCD1连锁的家族中进行的OVOL2突变分析显示，c.-307T>C变异与受累表型共分离。在筛查的其他26例先证者中，鉴定出1个杂合编码区变异和5个启动子区杂合变异，但根据等位基因频率，这些变异均不太可能致病。PPCD1和PPCD3位点的阵列CGH分别排除了涉及OVOL2或ZEB1的CNV的存在。与野生型序列相比，c.-307T>C变异在角膜内皮细胞中显示出增强的启动子活性，这与先前在另一种细胞类型中所证实的情况一致。
先前被确定为PPCD1病因的OVOL2启动子变异c.-307T>C，在确定PPCD1位点的原始家族中被鉴定出来。然而，在其他26例PPCD先证者中未能鉴定出推测的致病编码或非编码OVOL2或ZEB1变异，或涉及PPCD1和PPCD3位点的CNV，这表明其他遗传位点可能参与了PPCD的发病机制。
