Genetic variants at 13q12.12 are associated with high myopia in the Han Chinese population.

High myopia, which is extremely prevalent in the Chinese population, is one of the leading causes of blindness in the world. Genetic factors play a critical role in the development of the condition. To identify the genetic variants associated with high myopia in the Han Chinese, we conducted a genome-wide association study (GWAS) of 493,947 SNPs in 1088 individuals (419 cases and 669 controls) from a Han Chinese cohort and followed up on signals that were associated with p < 1.0 × 10(-4) in three independent cohorts (combined, 2803 cases and 5642 controls). We identified a significant association between high myopia and a variant at 13q12.12 (rs9318086, combined p = 1.91 × 10(-16), heterozygous odds ratio = 1.32, and homozygous odds ratio = 1.64). Furthermore, five additional SNPs (rs9510902, rs3794338, rs1886970, rs7325450, and rs7331047) in the same linkage disequilibrium (LD) block with rs9318086 also proved to be significantly associated with high myopia in the Han Chinese population; p values ranged from 5.46 × 10(-11) to 6.16 × 10(-16). This associated locus contains three genes-MIPEP, C1QTNF9B-AS1, and C1QTNF9B. MIPEP and C1QTNF9B were found to be expressed in the retina and retinal pigment epithelium (RPE) and are more likely than C1QTNF9B-AS1 to be associated with high myopia given the evidence of retinal signaling that controls eye growth. Our results suggest that the variants at 13q12.12 are associated with high myopia.

Exome sequencing identifies ZNF644 mutations in high myopia.

Myopia is the most common ocular disorder worldwide, and high myopia in particular is one of the leading causes of blindness. Genetic factors play a critical role in the development of myopia, especially high myopia. Recently, the exome sequencing approach has been successfully used for the disease gene identification of Mendelian disorders. Here we show a successful application of exome sequencing to identify a gene for an autosomal dominant disorder, and we have identified a gene potentially responsible for high myopia in a monogenic form. We captured exomes of two affected individuals from a Han Chinese family with high myopia and performed sequencing analysis by a second-generation sequencer with a mean coverage of 30× and sufficient depth to call variants at ∼97% of each targeted exome. The shared genetic variants of these two affected individuals in the family being studied were filtered against the 1000 Genomes Project and the dbSNP131 database. A mutation A672G in zinc finger protein 644 isoform 1 (ZNF644) was identified as being related to the phenotype of this family. After we performed sequencing analysis of the exons in the ZNF644 gene in 300 sporadic cases of high myopia, we identified an additional five mutations (I587V, R680G, C699Y, 3'UTR+12 C>G, and 3'UTR+592 G>A) in 11 different patients. All these mutations were absent in 600 normal controls. The ZNF644 gene was expressed in human retinal and retinal pigment epithelium (RPE). Given that ZNF644 is predicted to be a transcription factor that may regulate genes involved in eye development, mutation may cause the axial elongation of eyeball found in high myopia patients. Our results suggest that ZNF644 might be a causal gene for high myopia in a monogenic form.

An association study of the COL1A1 gene and high myopia in a Han Chinese population.

PURPOSE: Single nucleotide polymorphisms (SNPs) in the collagen type I (COL1A1) gene have been shown to be significantly associated with high myopia in a Japanese population. This present study was conducted to investigate whether COL1A1 is associated with high myopia in a Han Chinese population. METHODS: High myopia is defined by a spherical equivalent of less than or equal to -6.00 diopter sphere and an axial length longer than or equal to 26.0 mm in the affected eye. We genotyped rs2075555 and rs2269336 SNPs in COL1A1 in a Ha n Chinese group composed of 697 high myopia patients and 762 normal controls. RESULTS: Neither of the two SNPs showed significant association with high myopia (p(allelic)=0.252 for rs2075555, and p(allelic)=0.699 for rs2269336). CONCLUSIONS: Our study revealed that SNPs in COL1A1 are not significantly associated with high myopia in the Han Chinese population.

A novel mutation in BBS7 gene causes Bardet-Biedl syndrome in a Chinese family.

PURPOSE: To describe the clinical features of and identify a novel mutation in Bardet-Biedl syndrome 7 gene (BBS7) in a Chinese family. METHODS: Nineteen individuals at risk for inheriting Bardet-Biedl syndrome (BBS) in a Chinese family participated in the study. Physical examination was performed and blood was drawn for DNA extraction. Linkage analysis was conducted for all known BBS loci, and mutation screening of BBS7 gene and BBS12 gene was performed. RESULTS: A Chinese family with inherited BBS was identified. After performing linkage analysis on all 13 known loci, we found the disease phenotype of a Chinese family with BBS linked to a locus where BBS7 and BBS12 genes locate. CONCLUSIONS: This study describes a novel mutation in BBS7 causing BBS in a Chinese family. This is the first report that a mutation in a BBS gene causes BBS in a Chinese population. These results expand the spectrum of human disease associated with mutations of BBS7 since the initial three mutations in BBS7 were first identified in 2003.

HTRA1 variant increases risk to neovascular age-related macular degeneration in Chinese population.

Age-related macular degeneration (AMD) is a leading cause of irreversible visual impairment in the world. Advanced AMD can be divided into wet AMD (choroidal neovascularization) and dry AMD (geographic atrophy, GA). Drusen is characterized by deposits in the macula without visual loss and is an early AMD sign in the Caucasian population. rs11200638 in the promoter of HTRA1 has recently been shown to increases the risk for wet AMD in both Caucasian and Hong Kong Chinese populations. In order to replicate these results in a different cohort, we genotyped rs11200638 for 164 Chinese patients (90 wet AMD and 74 drusen) and 106 normal controls in a Han Mainland Chinese cohort. The genotypes were compared using chi square analysis for an additive allelic model. rs11200638 was significantly associated with wet AMD (p=5.00x10(-12)). Unlike in the Caucasian population, the risk allele of rs11200638 was not associated with drusen in our Chinese population. These findings confirm the association of HTRA1 with wet AMD.