Analysis of Phenotypes Associated with Deficiency of PAX6 Haplotypes in Chinese Aniridia Families

Objective To examine the clinical phenotype and genetic deficiencies present in Chinese aniridia families with PAX6 haplotype deficiency.Methods A comprehensive questionnaire and ophthalmological assessments were administered to both affected patients and unaffected relatives.The clinical feature analysis included the evaluation of visual acuity,intraocular pressure,slit-lamp anterior segment examination,fundus photography,and spectral domain optical coherence tomography.To identify the mutation responsible for aniridia,targeted next-generation sequencing was used as a beneficial technique.Results A total of 4 mutations were identified,consisting of two novel frameshift mutations(c.314delA,p.K105Sfs*33 and c.838_845dup AACACACC,p.S283Tfs*85),along with two recurring nonsense mutations(c.307C>T,p.R103X and c.619A>T,p.K207*).Complete iris absence,macular foveal hypoplasia,and nystagmus were consistent in these PAX6 haplotype-deficient Chinese aniridia families,while corneal lesions,cataracts,and glaucoma exhibited heterogeneity both among the families and within the same family.Conclusion In our study,two novel PAX6 mutations associated with aniridia were identified in Chinese families,which expanded the phenotypic and genotypic spectrum of PAX6 mutations.We also analyzed the clinical characteristics of PAX6 haplotype deficiency in Chinese aniridia families.

Detection of Novel BEST1 Variations in Autosomal Recessive Bestrophinopathy Using Third-generation Sequencing

Objective:Autosomal recessive bestrophinopathy(ARB),a retinal degenerative disease,is characterized by central visual loss,yellowish multifocal diffuse subretinal deposits,and a dramatic decrease in the light peak on electrooculogram.The potential pathogenic mechanism involves mutations in the BEST1 gene,which encodes Ca2+-activated Cl−channels in the retinal pigment epithelium(RPE),resulting in degeneration of RPE and photoreceptor.In this study,the complete clinical characteristics of two Chinese ARB families were summarized.Methods:Pacific Biosciences(PacBio)single-molecule real-time(SMRT)sequencing was performed on the probands to screen for disease-causing gene mutations,and Sanger sequencing was applied to validate variants in the patients and their family members.Results:Two novel mutations,c.202T>C(chr11:61722628,p.Y68H)and c.867+97G>A,in the BEST1 gene were identified in the two Chinese ARB families.The novel missense mutation BEST1 c.202T>C(p.Y68H)resulted in the substitution of tyrosine with histidine in the N-terminal region of transmembrane domain 2 of bestrophin-1.Another novel variant,BEST1 c.867+97G>A(chr11:61725867),located in intron 7,might be considered a regulatory variant that changes allele-specific binding affinity based on motifs of important transcriptional regulators.Conclusion:Our findings represent the first use of third-generation sequencing(TGS)to identify novel BEST1 mutations in patients with ARB,indicating that TGS can be a more accurate and efficient tool for identifying mutations in specific genes.The novel variants identified further broaden the mutation spectrum of BEST1 in the Chinese population.

Heparanase-1 activities in the development of laser induced choroidal neovascularization

AIM: To investigate the role of heparanase-1 in laser-induced choroidal neovascularization (CNV). METHODS: Experimental CNV was induced by krypton laser photocoagulation in 15 male Brown Norway rats. Fundus fluorescein angiography and histopathological examination were performed in observing the CNV development. The expression and distribution of heparanase-1 protein in the laser lesions were determined by immunohistochemistry and western blotting analysis. RESULTS: The success rate of laser induced CNV was approximately 75% on 3-4 weeks after laser photo-coagulation. The protein levels of heparanase-1 increased significantly in the retina-choroidal complex of CNV models when compared to normal rat eyes (P 【 0.01). Immunostaining confirmed strong heparanase-1 expressions in all laser lesions, and it displayed to be highest at the newly formed blood vessels within the fibrovascular complex in the subretinal space. CONCLUSION: Heparanase-1 is closely involved in the development of laser induced CNV.

Various phenotypes of autosomal dominant cone-rod dystrophy with cone-rod homeobox mutation in two Chinese families

AIM:To present the clinical manifestations of 5 autosomal dominant cone-rod dystrophy(ad CORD)patients from two Chinese families with cone-rod homeobox(CRX)mutation(p.R41W),and to explore the clinical heterogeneity of ad CORD with CRX mutation(p.R41W).METHODS:Interrogation and ophthalmological examinations were undertaken in all patients and unaffected members.Analysis of clinical features was performed by visual acuity,slit lamp examination,visual field examination,fundoscopy,autofluorescence and spectral domain optical coherence tomography.Targeted next-generation sequencing was applied as a useful tool to identify the causative mutation of CORD genes.RESULTS:A CRX missense mutation c.121C>T was identified in all patients,resulting in an amino acid change from arginine acid to tryptophan(p.R41W).The patients presented with early onset,progressive and different severities with CORD.CONCLUSION:This is the first report of the clinical phenotype of CRX mutation(p.R41W)in Chinese families,and the mutation can lead to a wide range of various retinal phenotypes.