Clinical Characteristics And Genetic Diversity Study Of Familial Exudative Vitreoretinopathy

Purpose: To observe and analyze the clinical and genetic diversity of the families with familial exudative vitreoretinopathy(FEVR).FEVR shows its diversity not only in clinical manifestations but also in the pathogenetic process and hereditary mode,and its gene polymorphism and clinical manifestation correlates with each other.Herein,we detect the potential pathogenic variants of FZD4,LRP5,NDP,TSPAN12,ZNF408 and KIF11 genes in Chinese FEVR population,and provide better guidance for clinical diagnosis and treatment of FEVR through a more comprehensive understanding of various clinical manifestations and multiple genetic patterns of FEVR.Methods: A retrospective study was conducted on 976 patients diagnosed as FEVR in the Department of Ophthalmology of Xinhua Hospital affiliated to Shanghai Jiaotong University and the Ophthalmology Hospital of Tianjin Medical University from January 2010 to December 2018.Among those 976 patients,722 consented to familial genetic testing,and their genome DNA were analyzed by next-generation sequencing,and afterwards,the selected mutant sequences were verified by sanger sequencing.The potential pathogenicity of the mutation site was analyzed by computer analysis and variation co-separation.The probands and their parents underwent a comprehensive ophthalmological examination appropriate to their age.The chief complaint,sex,gestational age,side of the eye,visual acuity,intraocular pressure,ocular examination,imaging examination,family history,history of treatments,etc.Of all the probands were collected.The severity of FEVR was satged and the other diseases with similar clinical manifestations were excluded.At the same time,normal healthy persons were selected as the control group.(1)Observe the clinical diversity of different genes.(2)Compare the genetic diversity of different genes and analyze the mutation frequency of LRP5,FZD4,ZNF408,NDP,TSPAN12 and KIF11 genes in FEVR family cohort and control cohort.(3)Compare the clinical prognosis of different genotypes.Results:(1)By reviewing the medical history and clinical manifestations of 976 FEVR patients,43 FEVR patients with multiple clinical manifestations were found(4.4%,43/976),including 17 cases with premature delivery history,3 cases with retinitis pigmentosa,3 morning glory syndrome,4 reverse drag-disc lesions,2 epimacular membrane,2 choroidal neovascularization,1 persistent hyperplasia primary vitreous,1 choroidal coloboma,1 optic pit,1retinal vasculitis,1 traumatic vitreous hemorrhage,2 Coats-like disease,3 eyelid ptosis,1 case with ocular cellulitis like manifestation,and 1 case with uveitis manifestation.(2)By reviewing the genetic reports of 722 FEVR patients,366 patients with positive and suspected positive genetic tests were found(50.7%,366/722),and 206 patients(56.28%,206/366)had positive family history.Among them,335 cases were single gene positive(46.4%,335/722).A total of 269 rare variants were detected,including 134 potential pathogenic variants(PPVs)and 135 variants with unknown significance,in which 77 PPVs and 131 VUS were newly discoverd.The potential pathogenicity variation of LRP5,FZD4,TSPAN12,NDP,ZNF408 and KIF11 accounted for 15.58%,22.01%,29.87%,14.29%,16.89% and 1.3% of the sequence respectively,of which mainly was missense mutation,frameshift mutation and termination variation.Thirty-four FEVR families(4.71%),in which the genetic test of both parents was positive,were identified.A total of 65 mutations were detected,of which missense mutations of LRP5 gene was the most common.Thereinto,compared wiht the 65 FEVR families(accounting for 9% of the sample,65/722)with LRP5 gene mutations in only one parent,the severe degree of FEVR is much higher in the 22 FEVR families(3.05%,22/722)with LRP5 gene mutations in both of the parents.(3)Among the 335 patients with single-gene positive or suspected positive,the male-to-female ratio was 2.48:1.There is a certain correlation between the clinical phenotype and mutation type,in which the clinical phenotype of patients with malignant variation is much severer than that of patients with missense mutation,and mainly in both eyes.And the proportion of LRP5 and FZD4 mutation is the highest,and the clinical phenotype of patients with NDP mutation is the severest,and with the highest symmetry,mainly happend binocularly,accounting for 79.2%.KIF11 spontaneous mutation accounted for the majority,accompanied by microcephaly and choroidal atrophy.The clinical phenotype of patients with ZNF408 mutation was with minimum symptom,mainly in both eyes,accounting for 50%,followed by LRP5.TSPAN12 accounted for the highest familial hereditary ratio with a lower symmetry.71.96% of the gene mutation were found within 3 years old.The severity of most of the affected eyes in FEVR patients was more than stage 3,while the parants of the children who carried pathogenic gene were mostly asymptomatic or with mild clinic symptoms.(4)Nomatter what the genotype is,most of the FEVR patients within 1-year-old were treated with sugery.70.95% of the FEVR patients under 1-year-old reached a grade-5 level of disease severity.The transcorneal vitrectomy with/without lentectomy were performed on the under-threes with severe level of FEVR.Pars plana vitrectomy combined with silicone oil or C3F8 injection,scleral buckling or scleral cerclage was performed on older patients with severe degree of disease.Patients within grade 1-3 were mostly given intravitreous drug injection and/or retina photocoagulation.According to the severity of the disease,the prognosis included funnel-like expansion of the retina,unfolding of the posterior retinal pole,hyphema,closure of pupil,cornea degeneration,secondary glaucoma,cholesterol crystallization,eyeball atrophy and so on.Some patients have good prognosis and stable condition.Conclusion:(1)This is the first study reporting FVER patients with multiple ocular abnormalities.The clinical manifestations and complications of FEVR are diverse.(2)Our study extended the PPVs spectrum of FEVR.There is a certain correlation between clinical phenotype and mutation type.Probands who carry NDP and KIF11 variants have more severe clinical manifestations.The discrepancy between LRP and FZD4 phenotype is more significant than that between TSPAN12 and NDP.The variation of LRP5 and FZD4 accounted for the highest proportion,followed by KIF11 spontaneous mutation and accompanied by microcephaly and choroidal atrophy.The disease severity of most FEVR patients have past grade 3,while the parents with FEVR pathogenic gene variants mostly showed no or mild clinical symptoms.(3)This is the first study on the correlation between clinical phenotype and genotype in the patients with positive pathogenic gene.LRP5 mutation is most common in FEVR families,and missense mutation is the most common type.There is no significant correlation between the severity of clinical symptoms and the type of gene variation.The disease severity of patients with both parents carrying LRP5 gene variant is much higher than the patients with only one parent carrying LRP5 gene variant.The disease severity of patients with both parents carrying LRP5 gene variant is much higher than the patients with only one parent carrying LRP5 gene variant.The proportion of severe binocular symptoms is much higher in the probands with both LRP5 gene positive parents than that in probands with only one LRP5 gene positive parent.The mutation rate of LRP5 gene in 87 patients was significantly higher than that in normal subjects.Through the statistics of the known pathogenic genes mutation rate of FEVR in different populations,we found out that there may be a positive correlation between the clinical severity of FEVR and the number of FEVR pathogenic gene mutation sites.(4)According to the severity,scope and morphology of FEVE,we performed transcorneal vitrectomy with/without lentectomy,scleral buckling or pars plana vitrectomy individually on the FEVR patients aused by different gene mutations and aquired certain effect.Among all the patients with different kinds of gene variants,the proportion of surgical treatment is much higher in patients under 1-year-old,and 70.95% of the FEVR patients under 1-year-old reached a grade-5 level of disease severity,which showed that the earlier and severer the onset of FEVR,the worse the prognosis will be.