De novel heterozygous copy number deletion on 7q31.31-7q31.32 involving TSPAN12 gene with familial exudative vitreoretinopathy in a Chinese family

AIM:To investigate the genetic and clinical characteristics of patients with a large heterozygous copy number deletion on 7q31.31-7q31.32.METHODS:A family with familial exudative vitreoretinopathy(FEVR)phenotype was included in the study.Whole-exome sequencing(WES)was initially used to locate copy number variations(CNVs)on 7q31.31-31.32,but failed to detect the precise breakpoint.The long-read sequencing,Oxford Nanopore sequencing Technology(ONT)was used to get the accurate breakpoint which is verified by quantitative real-time polymerase chain reaction(QPCR)and Sanger Sequencing.RESULTS:The proband,along with her father and younger brother,were found to have a heterozygous 4.5 Mb CNV deletion located on 7q31.31-31.32,which included the FEVRrelated gene TSPAN12.The specific deletion was confirmed as del(7)(q31.31q31.32)chr7:g.119451239_123956818del.The proband exhibited a phase 2A FEVR phenotype,characterized by a falciform retinal fold,macular dragging,and peripheral neovascularization with leaking of fluorescence.These symptoms led to a significant decrease in visual acuity in both eyes.On the other hand,the affected father and younger brother showed a milder phenotype.CONCLUSION:The heterozygous CNV deletion located on 7q31.31-7q31.32 is associated with the FEVR phenotype.The use of long-read sequencing techniques is essential for accurate molecular diagnosis of genetic disorders.

The role of intravitreal ranubizumab in the treatment of familial exudative vitreoretinopathy of stage 2 or greater

AIM： To evaluate the role of intravitreal ranubizumab （IVR） in the treatment of familial exudative vitreoretinopathy （FEVR） of stage 2 or greater either as primary or an ajunct to conventional treatments. METHODS： Retrospective, non-controlled clinical study. Thirty patients （37 eyes） diagnosed with FEVR were enrolled. Twenty patients （66.67%） were male and 10 patients （33.33%） were female. Age ranged from 0.4 to 35 years old （median 3y）. IVR was used either as primary or as a combined therapy according to the retinal neovasuclar activities. The follow up ranged from 1 to 57mo with mean 16.73±15.73 （median 11）mo. The treatment effect of retinal neovasuclar activites were recorded as well as the ocular and systemic side effects. RESULTS： Among 30 patients （37 eyes）, 10 eyes received single IVR, 1 eye received 2 injections. Three eyes were treated with IVR and simutanous laser photocoagulation. Laser indirect ophthalmoscopy （LIO） was applied in 5 eyes 1mo after the primary IVR. Seven eyes were treated surgically following the primary IVR due to persistent retinal neovasuclar activities and retinal traction. IVR was used as combined treatment with vitrectomy in 11 eyes. Retinal neovascular regression was notified 1mo following the primary IVR in all eyes. Neither systemic nor ocular complications were recorded. CONCLUSION： IVR may be an effective modality in the treatment of FEVR either as primary or as an ajunct to the conventional therapies. The long term effect and safty of IVR still need further research.

Atypical Adams-Oliver syndrome with typical ocular signs of familial exudative vitreoretinopathy

AIM:To report an atypical Adams-Oliver syndrome(AOS)family with typical ocular signs of familial exudative vitreoretinopathy(FEVR).METHODS:A patient with visible avascular area and obvious non-perfusion zone in the peripheral retina with systemic signs of AOS was reported.Familial and personal characteristics were collected for the patient and his sister.Gene sequencing and ophthalmic examinations including fluorescein angiography were all performed for the whole family.RESULTS:Two novel mutations of DOCK6(c.1396C>T and c.4796G>A)were identified in the proband and his family,and two compound heterozygous mutations were revealed in the proband and his sister.The patient and his sister showed physical deformities and mental abnormalities while FEVR mimicking retinal disorder can also be defined.No remarkable ocular or systemic abnormality can be observed for their parents.Peripheral retinal non-perfusion area,obvious abnormal vascularization or even retinal fold were observed in the proband and his sister,while only small avascular zone was identified for their parents.CONCLUSION:This is the first genetic authenticated AOS case mimicked as FEVR with genetic sequencing of a family.For the patients with ocular phenotype of FEVR,further examination should be performed if the systemic or mental abnormalities exist.

Defective EMC1 drives abnormal retinal angiogenesis via Wnt/β-catenin signaling and may be associated with the pathogenesis of familial exudative vitreoretinopathy

Endoplasmic reticulum(ER)membrane protein complex(EMC)is required for the co-translational insertion of newly synthesized multi-transmembrane proteins.Compromised EMC function in different cell types has been implicated in multiple diseases.Using inducible genetic mouse models,we revealed defects in retinal vascularization upon endothelial cell(EC)specific deletion of Emc1,the largest subunit of EMC.Loss of Emc1 in ECs led to reduced vascular progression and vascular density,diminished tip cell sprouts,and vascular leakage.We then performed an unbiased transcriptomic analysis on human retinal microvascular endothelial cells(HRECs)and revealed a pivotal role of EMC1 in theβ-catenin signaling pathway.Further in-vitro and in-vivo experiments proved that loss of EMC1 led to compromisedβ-catenin signaling activity through reduced expression of Wnt receptor FZD4,which could be restored by lithium chloride(LiCl)treatment.Driven by these findings,we screened genomic DNA samples from familial exudative vitreoretinopathy(FEVR)patients and identified one heterozygous variant in EMC1 that co-segregated with FEVR phenotype in the family.In-vitro expression experiments revealed that this variant allele failed to facilitate the expression of FZD4 on the plasma membrane and activate theβ-catenin signaling pathway,which might be a main cause of FEVR.In conclusion,our findings reveal that variants in EMC1 gene cause compromisedβ-catenin signaling activity,which may be associated with the pathogenesis of FEVR.