The gene for autosomal dominant familial exudative vitreoretinopathy (Criswick-Schepens) on the long arm of chromosome 11

Diversity of retinal vascular anomalies in patients with familial exudative vitreoretinopathy

PURPOSE

To describe the diversity of clinical findings associated with familial exudative vitreoretinopathy (FEVR) using wide-field angiography and to update the current classification system.

DESIGN

Retrospective case series at a single tertiary referral vitreoretinal practice.

PARTICIPANTS

A total of 174 eyes of 87 subjects were studied.

METHODS

A retrospective chart review was conducted of patients with a diagnosis of FEVR between January 2011 and January 2013 at a single tertiary care retina practice. Data were collected from patient charts, including sex, gestational age at birth, age at presentation, referring diagnosis, family history, prior ocular surgery, clinical presentation, and diagnostic imaging in each eye. Inclusion criteria included clinical diagnosis of FEVR in patients referred to our clinic for evaluation of decreased vision. Patients were excluded if a diagnosis of FEVR could not be made.

MAIN OUTCOME MEASURES

Clinical and angiographic findings.

RESULTS

A total of 87 subjects met the inclusion criteria for this study. A broad spectrum of previously undescribed clinical and angiographic findings were associated with FEVR on wide-field angiography. These findings can be grossly divided into anatomic and functional changes. Anatomic changes include aberrant circumferential peripheral vessels, venous and arterial tortuosity, late-phase disc leakage, central and peripheral telangiectasias, capillary anomalies, and capillary agenesis. Functional changes include venous-venous shunting, delayed arteriovenous transit, and delayed or absent choroidal perfusion on fluorescein angiography.

CONCLUSIONS

Familial exudative vitreoretinopathy has a wide range of unrecognized or under-recognized clinical and angiographic findings that are easily identified using wide-field fluorescein angiography. These novel findings have led to an update of the original FEVR classification scheme and more complete characterization of early stages of FEVR.

High prevalence of peripheral retinal vascular anomalies in family members of patients with familial exudative vitreoretinopathy

OBJECTIVE

To describe the prevalence and severity of familial exudative vitreoretinopathy (FEVR) in asymptomatic relatives of known symptomatic FEVR patients.

DESIGN

Uncontrolled and retrospective case series at a single tertiary referral vitreoretinal practice.

PARTICIPANTS

A total of 148 eyes of 74 subjects were studied.

METHODS

A retrospective chart review was conducted of patients with a diagnosis of FEVR between January 2011 and January 2013 at a single tertiary care retina practice. Data were collected from patient charts, including sex, gestational age at birth, age at presentation, referring diagnosis, family history, prior ocular surgery, clinical presentation, and diagnostic imaging in each eye. Inclusion criteria included confirmed clinical diagnosis of FEVR in patients referred to our clinic for evaluation of decreased vision. Patients were excluded if a definitive diagnosis of FEVR could not be made.

MAIN OUTCOME MEASURES

Clinical and angiographic findings.

RESULTS

A total of 74 subjects from 17 separate families met the inclusion criteria for this study. There were an average of 4.4 subjects per family included in this study. The cohort was 55% male and included 17 patients and 57 family members who agreed to undergo genotyping, examination, and diagnostic imaging. Forty-three percent of FEVR patients had detectable mutations in FZD4, NDP, or TSPAN12. Only 8% of the cohort reported a positive family history of FEVR in a first-degree relative. Among the index patients, 76% had clinical stage 3, 4, or 5 FEVR and 24% had stage 1 or 2 FEVR. Among the asymptomatic family members screened, 58% demonstrated clinical or angiographic findings consistent with stage 1 or 2 FEVR and 21% demonstrated clinical or angiographic findings consistent with stage 3, 4, or 5 FEVR.

CONCLUSIONS

Asymptomatic family members of FEVR patients frequently have early manifestations of FEVR (stage 1 or 2). Early-stage FEVR may progress to more advanced stages, which can result in vision loss. These data support the use of angiographic screening and clinical examination in immediate relatives of patients with symptomatic FEVR.

A novel case of bilateral high myopia, cataract, and total retinal detachment associated with interstitial 11q deletion

PURPOSE

Jacobsen syndrome, also known as 11q deletion syndrome, is a rare condition characterized by multiple anomalies, including developmental delay, cardiac abnormalities, blood dyscrasias, distal limb abnormalities, craniofacial anomalies, and variable ophthalmic manifestations. The syndrome's phenotype is due to a terminal deletion and is usually severely debilitating, frequently associated with fatality. Interstitial deletions, not involving the terminal end, have been associated with a more variable and less severe phenotype.

METHODS

Herein, we describe a case of interstitial 11q deletion in a 16 year-old female with associated systemic and craniofacial abnormalities as well as a novel combination of ocular findings, specifically strabismus, high myopia, bilateral cataracts, and bilateral total retinal detachments.

RESULTS

This case report highlights the necessity for a detailed ophthalmic examination of patients with both interstitial and terminal deletions of the long arm of chromosome 11.

SNPs: impact on gene function and phenotype

Single nucleotide polymorphism (SNP) is the simplest form of DNA variation among individuals. These simple changes can be of transition or transversion type and they occur throughout the genome at a frequency of about one in 1,000 bp. They may be responsible for the diversity among individuals, genome evolution, the most common familial traits such as curly hair, interindividual differences in drug response, and complex and common diseases such as diabetes, obesity, hypertension, and psychiatric disorders. SNPs may change the encoded amino acids (nonsynonymous) or can be silent (synonymous) or simply occur in the noncoding regions. They may influence promoter activity (gene expression), messenger RNA (mRNA) conformation (stability), and subcellular localization of mRNAs and/or proteins and hence may produce disease. Therefore, identification of numerous variations in genes and analysis of their effects may lead to a better understanding of their impact on gene function and health of an individual. This improved knowledge may provide a starting point for the development of new, useful SNP markers for medical testing and a safer individualized medication to treat the most common devastating disorders. This will revolutionize the medical field in the future. To illustrate the effect of SNPs on gene function and phenotype, this minireview focuses on evidences revealing the impact of SNPs on the development and progression of three human eye disorders (Norrie disease, familial exudative vitreoretinopathy, and retinopathy of prematurity) that have overlapping clinical manifestations.

[Mutations of the frizzled-4 gene. Their impact on medical care of patients with autosomal dominant exudative vitreoretinopathy]

PURPOSE

Autosomal dominant (familial) exudative vitreoretinopathy (adEVR) is a rare, congenital disease of the retinal vascular system, which may lead to blindness in severely affected eyes. One of the causative disease genes is located on chromosome 11q13-q23 and codes for "frizzled-4" (FZD4), a protein involved in vascular differentiation.

METHOD

Examination of two families with adEVR over six and four generations and FZD4 mutation analysis.

RESULTS

In family I, 18 examined affected members exhibited a heterozygous missense mutation (p.G492R) in the FZD4 gene. In family II, four examined family members were affected and carried a heterozygous deletion of five nucleotides (c.1286del5). Both mutations are novel and showed 100% penetrance and variable expressivity.

CONCLUSIONS

With detection of the "family-specific" FZD4 gene mutation, carriers amongst offspring of affected family members can be identified at an early time. The complete penetrance of FZD4 mutations may justify abandoning repeated examinations of offspring of affected family members, if no mutations were detected in FZD4.

Complexity of the genotype-phenotype correlation in familial exudative vitreoretinopathy with mutations in theLRP5and/orFZD4genes

Familial exudative vitreoretinopathy (FEVR) is a hereditary blinding disorder that features defects in retinal vascular development. The mutations in the genes encoding the Wnt receptor pair, frizzled 4 (FZD4) and low-density-lipoprotein receptor-related protein 5 (LRP5), have been shown to cause FEVR. In this study we screened 56 unrelated patients with FEVR (31 familial and 25 simplex cases) for possible mutations in LRP5 and FZD4. Six novel mutations in either LRP5 or FZD4 were identified in six familial cases. Four novel mutations in LRP5 and one known mutation in FZD4 were detected in three simplex cases, and two of these patients carried compound heterozygous mutations in LRP5. Remarkably, c.1330C>T [p.R444C] in LRP5 was found in the family in which c.1250G>A [p.R417Q] in FZD4 had previously been identified. The phenotype of these patients suggested a synergistic effect of the two mutations in the independent FEVR-causing genes. We also demonstrated that reduced bone density is a common feature in patients with FEVR who harbor LRP5 mutations. The profile of the mutations obtained in the current study further illustrates the complexity of the disease and provides a better understanding of the spectrum, frequencies, and genotype-phenotype correlation.

Mutations in LRP5 or FZD4 underlie the common familial exudative vitreoretinopathy locus on chromosome 11q

Familial exudative vitreoretinopathy (FEVR) is an inherited blinding disorder of the retinal vascular system. Autosomal dominant FEVR is genetically heterogeneous, but its principal locus, EVR1, is on chromosome 11q13-q23. The gene encoding the Wnt receptor frizzled-4 (FZD4) was recently reported to be the EVR1 gene, but our mutation screen revealed fewer patients harboring mutations than expected. Here, we describe mutations in a second gene at the EVR1 locus, low-density-lipoprotein receptor-related protein 5 (LRP5), a Wnt coreceptor. This finding further underlines the significance of Wnt signaling in the vascularization of the eye and highlights the potential dangers of using multiple families to refine genetic intervals in gene-identification studies.

Frizzled 4 gene (FZD4) mutations in patients with familial exudative vitreoretinopathy with variable expressivity

AIMS

To search for mutations in the frizzled 4 (FZD4) gene in patients with familial exudative vitreoretinopathy (FEVR) and to delineate the defective gene associated clinical features.

METHODS

Direct sequencing following polymerase chain reaction of exons of FZD4 was performed for 24 probands with FEVR (18 familial and six sporadic), and some of their families. Clinical symptoms among individuals with mutations were assessed.

RESULTS

Four novel mutations were identified in four patients with familial and one with sporadic FEVR. Three of these mutations were missense (M105V, R417Q, and G488D) and one was a nonsense change (W319X). M105V, R417Q, and G488D co-segregated with the disease. None of these sequence changes was found among 300 chromosomes from 150 healthy volunteers. The severity of vitreoretinopathy in the individuals involved in this study varied, but no patient with mutations in FZD4 exhibited rhegmatogenous retinal detachment although this pathology is thought to be the most common type of retinal detachment in FEVR.

CONCLUSION

FZD4 gene mutations were found in some cases of autosomal dominant and sporadic FEVR. FZD4 mutations were responsible for FEVR with variable clinical manifestations.

Mutant frizzled-4 disrupts retinal angiogenesis in familial exudative vitreoretinopathy

Familial exudative vitreoretinopathy (FEVR) is a hereditary ocular disorder characterized by a failure of peripheral retinal vascularization. Loci associated with FEVR map to 11q13-q23 (EVR1; OMIM 133780, ref. 1), Xp11.4 (EVR2; OMIM 305390, ref. 2) and 11p13-12 (EVR3; OMIM 605750, ref. 3). Here we have confirmed linkage to the 11q13-23 locus for autosomal dominant FEVR in one large multigenerational family and refined the disease locus to a genomic region spanning 1.55 Mb. Mutations in FZD4, encoding the putative Wnt receptor frizzled-4, segregated completely with affected individuals in the family and were detected in affected individuals from an additional unrelated family, but not in normal controls. FZD genes encode Wnt receptors, which are implicated in development and carcinogenesis. Injection of wildtype and mutated FZD4 into Xenopus laevis embryos revealed that wildtype, but not mutant, frizzled-4 activated calcium/calmodulin-dependent protein kinase II (CAMKII) and protein kinase C (PKC), components of the Wnt/Ca(2+) signaling pathway. In one of the mutants, altered subcellular trafficking led to defective signaling. These findings support a function for frizzled-4 in retinal angiogenesis and establish the first association between a Wnt receptor and human disease.

Vitrectomy for rhegmatogenous or tractional retinal detachment with familial exudative vitreoretinopathy

OBJECTIVE

To examine the anatomic features and surgical indications of familial exudative vitreoretinopathy (FEVR) complicated with rhegmatogenous or tractional retinal detachment.

DESIGN

Retrospective noncomparative case series.

PARTICIPANTS

Twenty-eight eyes of 25 patients who had either clinically suspected or fully diagnosed FEVR. Of these, 25 had rhegmatogenous retinal detachment, 2 had tractional retinal detachment, and 1 had tractional retinal detachment plus vitreous hemorrhage.

INTERVENTIONS

The authors carefully observed the vitreoretinal interface during surgery, studied the clinical and anatomic features of FEVR, and then evaluated the surgical results.

RESULTS

The vitreoretinal adhesions were so strong in the peripheral avascular area that iatrogenic retinal breaks easily occurred in 22 of 28 eyes. In all cases, the bimanual technique with vitreous scissors and forceps was required to dissect the posterior vitreous membrane from the retinal surface. The retina was reattached in 24 of 28 cases (85.7%), and visual acuity improved in 20 eyes (71.4%).

CONCLUSION

Dissection of the vitreous in the peripheral avascular area is very difficult in FEVR, and those patients for whom this procedure was not successfully performed may have a poorer prognosis.

Familial exudative vitreoretinopathy: surgical intervention and visual acuity outcomes

BACKGROUND

Familial exudative vitreoretinopathy (FEVR) is a hereditary condition that may lead to vitreous hemorrhage and traction retinal detachment necessitating surgical intervention. In this paper we review the results of surgery on seven such patients (eight eyes).

METHODS

Seven patients (eight eyes) were followed up after surgery that had been performed because of vitreous hemorrhage and/or traction retinal detachment due to FEVR, in an effort to evaluate outcomes. Parameters that were noted were the current age, gender, age at the time of first surgery, length of follow-up and postoperative retinal status and visual acuity.

RESULTS

Seven patients (eight eyes) ranging in age from 6 months to 44 years with a mean of 24.7 and a median of 26 years were followed. There were three females and four males. The lowest age at which surgery was first performed was 6 months and the highest was 28 years, with a mean of 14.7 and a median of 17 years. Six of the 8 eyes were reattached following surgery, although some required multiple procedures.

CONCLUSION

Vitreoretinal surgery may be of benefit in helping to preserve some degree of vision in eyes of patients with FEVR who develop vitreous hemorrhage and/or retinal detachment.

Familial exudative vitreoretinopathy linked to D11S533 in a large Asian family with consanguinity

Familial exudative vitreoretinopathy (FEVR) is a disorder characterised by peripheral retinal vascularisation with subsequent traction of retinal vessels and detachment. Recently, autosomal dominant FEVR (ad FEVR) has been mapped to 11q13 by linkage in four northern European families. We describe a large consanguineous Asian family in which the severity of the proband's eye disease suggested homozygosity for a disease allele. Thirty family members were assessed by ophthalmological examination and fluorescein angiography. Thirteen had unequivocal features of FEVR. A further two were classified as unknown. Two point linkage analysis for DIIS533 and FEVR generated a lod score of 5.55 at a recombination fraction of 0.00. This supports autosomal dominant inheritance and demonstrates genetic homogeneity for the ad FEVR disease locus. The severely affected proband was heterozygous for alleles at this closely linked locus. Other causes, including non-genetic factors, should be considered to explain the extreme variability characteristic of ad FEVR.