Blindness from bilateral bullous retinal detachment: tragedy of a Nigerian family

OBJECTIVE

To present a scourge of blindness possibly due to an inherited condition causing retinal detachment in 3 siblings

METHODS

In February 2004, three siblings from a monogamous family from Ipetu-Ijesha in Osun state, Nigerian presented to the author consecutively with history of visual impairment/ blindness. A detailed history and comprehensive ocular examination was conducted on each of them. Information obtained included patients demographic, family history of blindness, eye diseases and other medical conditions. Visual acuity assessment, slit lamp examination, direct and indirect ophthalmoscopy, intra-ocular pressure measurement, visual field test and systemic evaluation were conducted on each of the patients.

RESULTS

Two males and a female patient from the same parents who were systemically healthy are reported. Their ages were 67 years, 58 years and 52 years respectively. Each presented with bilaterally poor vision ranging from 6/36 to no light perception, intra-ocular pressure ranging between 6 and 18mmHg and bilateral grayish white bullous retinal detachment.

CONCLUSION

The mode of inheritance in these patients was most probably autosomal dominant or X-linked recessive. Ignorance and poverty causing failure to seek prompt specialize eye care were responsible for blindness in these siblings.

Outcomes of surgery for retinal detachment in patients with Stickler syndrome: a comparison of two sequential 20-year cohorts

BACKGROUND

Stickler syndrome is a hereditary oculo-systemic disorder where patients are predisposed to retinal detachments which are often complex and challenging to manage. Significant progress has been made regarding the molecular genetics of the condition; however, there is little recent literature on surgery for retinal detachment in Stickler syndrome. Our aim is to describe a population of Stickler patients presenting to Moorfields Eye Hospital with detachment from 1986 to 2003. We looked at patient characteristics, characteristics of detachment, management and anatomical and functional outcomes. We also aim to compare this group from 1986 to 2003 with a past group of Stickler patients treated at Moorfields between 1965 and 1985, reported by (Billington et al. in Trans Ophthalmol Soc UK 104:875-879, 1985). This comparison of 20-year matched cohorts examined patient characteristics, features of detachment, management and anatomical outcome in the two groups using the same definitions as the earlier authors.

RESULTS

In the Stickler group from 1986 to 2003, complete re-attachment rate was 67% for primary scleral-buckle surgery, 84.2% for primary vitrectomy and 78.57% for all surgery in 30 eyes of 23 patients. Overall in this group there was an average increase in Logmar visual acuity of 0.33 and 0.32 in patients undergoing primary cryo-buckle and primary vitrectomy surgery respectively. When comparing the two groups using Fisher's exact test, we found that the group from 1986 to 2003 had significant improvement in re-attachment for detachments with multiple tears and for vitrectomy surgery, compared with the group from 1965 to 1985.

CONCLUSIONS

This study shows that despite complicated surgery and often multiple procedures, good anatomical outcomes were achieved as well as useful functional visual results after retinal detachment surgery in Stickler patients. It would also appear that when comparing the group of Stickler patients from 1986 to 2003 with the group from 1965 to 1985 improvements were seen in outcome from vitrectomy surgery and surgery for multiple breaks probably due to advances in technique and technology in vitreoretinal surgery, over the past 4 decades.

Missense and silent mutations in COL2A1 result in Stickler syndrome but via different molecular mechanisms

Stickler syndrome due to mutations in COL2A1 is usually the result of premature termination codons and nonsense mediated decay resulting in haploinsufficiency of type II collagen. Here we present two missense mutations and one apparently silent mutation that each result in Stickler syndrome, but via different molecular mechanisms. One alters the translation initiating ATG codon. The second mutation is a unique glycine substitution in the minor collagen helix of the procollagen. To our knowledge a glycine substitution has not previously been reported in this region of fibrillar procollagens. The third mutation appears to be a silent change altering a GGC codon to GGT both for glycine, but use of a splicing reporter assay demonstrates that it results in missplicing and a shift in the reading frame.

Further Support for the Common Variants in Complement Factor H (Y402H) and LOC387715 (A69S) Genes as Major Risk Factors for the Exudative Age-Related Macular Degeneration

In developed countries, age-related macular degeneration (ARMD) is a common cause of blindness in the elderly. It is a clinically complex and genetically heterogeneous disorder. The etiology of the disorder may involve interactions between genetic and environmental factors. Recently it has been reported that a polymorphism in the complement factor H (CFH) and LOC387715 gene may determine the susceptibility of individuals to ARMD. In order to replicate and to determine the frequency of this polymorphism in ARMD patients, we have analyzed two unrelated families having exudative ARMD. Our analysis has identified the same common polymorphism (Y402H) in the CFH gene in one family and the A69S polymorphism in the LOC387715 gene in the second family. These results further support the notion that CFH and LOC387715 genes are the major risk factors for ARMD.

Cytokine gene polymorphisms in retinal detachment patients with and without proliferative vitreoretinopathy: a preliminary study

PURPOSE

Cytokines and other growth factors such as interleukins play an important role in the pathogenesis of proliferative vitreoretinopathy (PVR). Interindividual variations in cytokine production seem to correlate with some cytokine gene polymorphisms. The purpose of this study was to analyse the distribution of these cytokine gene variants in patients with rhegmatogenous retinal detachment (RD) with and without PVR.

METHODS

Single nucleotide polymorphisms were analysed for five cytokines: tumour necrosis factor-alpha (TNF-alpha), transforming growth factor-beta1 (TGF-beta1), interferon-gamma (IFN-gamma), interleukin-6 (IL-6) and interleukin-10 (IL-10). Patients were divided into two surgically treated groups of RD patients: group RD had 27 patients with RD, and group PVR had 31 patients with RD complicated by PVR. A control group was composed of 46 ethnically matched healthy individuals.

RESULTS

The genotype distribution of the TGF-beta1 codon 10 polymorphism differed between PVR and RD patients (p = 0.018) and between PVR patients and controls in codon 25 (p = 0.011). There was a higher frequency of TGF-beta1 codon 10 allele T in PVR patients compared with RD patients (p = 0.023). No statistically significant differences between groups were observed for the other polymorphisms examined.

CONCLUSION

An association between the TGF-beta1 genetic profile and the development of PVR was detected in this study. Further studies are necessary to confirm this finding and to establish its clinical relevance.

A mouse model for Stickler's syndrome: ocular phenotype of mice carrying a targeted heterozygous inactivation of type II (pro)collagen gene (Col2a1)

The influences of targeted heterozygous inactivation of type II (pro)collagen gene (Col2a1) on eye structures in the 15-month-old C57BL/6JOlaHsd mouse was studied. The eyes were collected from C57BL mice heterozygous for a targeted inactivation of one allele of the Col2a1 gene (Col2a1(+/-) mice). The eyes of C57BL mice with normal gene alleles were used as controls (Col2a1(+/+) mice). Ocular histology was analyzed from tissue sections, stained with hematoxylin and eosin, toluidine blue and alcian blue. Type II collagen was localized by immunohistochemistry. Hyaluronan (HA) was stained utilizing the biotinylated complex of the hyaluronan-binding region of aggrecan and link protein (bHABC). The anterior segment of the eye was well-formed in both genotypes, but typical folding of ciliary processes was decreased, while increased stromal extracellular matrix vacuolization was seen in the Col2a1(+/-) mice. In the lens of these mice, subcapsular extracellular matrix changes were observed. Differences in retinal structures or the number of the eyes with retinal detachment were not detected between the genotypes. In Col2a1(+/-) mice, staining for type II collagen was weaker in cornea, ciliary body, iris, lens, vitreous, retina, choroid and sclera than in the control mice. HA staining was detected in the extraocular tissues, ciliary body, iris and the choroid of both genotypes. HA staining was observed only in the vitreous body of the control animals. Heterozygous inactivation of Col2a1 gene causes structural defects in the murine eye. The observed structural changes in the ciliary body, lens and vitreous of the Col2a1(+/-) mice may represent ocular features found in the human Stickler syndrome, where the abnormalities result from COL2A1 gene mutations which lead to functional haploinsufficiency.

An evolutionary perspective on the photoreceptor damage response

PURPOSE

To review recent advances related to the response to photoreceptor damage and to place this knowledge in an evolutionary context.

DESIGN

Synthesis of published laboratory, clinical, and epidemiologic data.

METHODS

The authors have synthesized the principal published findings related to the mechanism and function of the photoreceptor damage response with the goal of trying to understand the selective pressures that shaped its evolution.

RESULTS

The past several years have seen considerable advances in understanding the molecular and cellular basis of the retina's response to photoreceptor damage. From their analysis of laboratory, clinical, and epidemiologic data, the authors suggest that the photoreceptor damage response may have evolved to counter the effects of retinal tears and detachment, infectious retinitis, and/or light damage.

CONCLUSIONS

If the natural response to photoreceptor damage can be fully defined, it may be possible to augment desirable aspects of the damage response and/or suppress undesirable ones in the context of a wide variety of photoreceptor diseases.

Type 1 Stickler syndrome: a histological and ultrastructural study of an untreated globe

AIMS

To present a histological and ultrastructural study of an untreated globe in a patient with genetically confirmed type 1 Stickler syndrome.

METHODS

Histological and electron microscopic examinations were performed on the enucleated globe from the proband of a pedigree with type 1 Stickler syndrome. Linkage analysis was carried out using polymorphic markers flanking the COL2A1 gene and the mutation was identified by direct sequencing.

RESULTS

The significant retinal abnormality was incarceration of vitreous collagen within glial strands on the inner surface of an atrophic and gliotic detached retina. The incarcerated collagenous layers contained glial cells and extended from the retina to form strands, some of which contributed to a retrolental membrane. Mutation screening detected a C to T mutation in exon 47 that inserted a premature termination codon into the reading frame of the mRNA. Sequence analysis of three of the four affected children confirmed that they were also heterozygous for the base change. The youngest child's DNA was not analysed.

CONCLUSIONS

The study represents the first evidence of abnormal interactions between pathological vitreous collagen and the inner retina in a patient with type 1 Stickler syndrome with a confirmed mutation in the COL2A1 gene.

Generation of transgenic mice with mild and severe retinal neovascularisation

AIM

To generate a mouse model for slow progressive retinal neovascularisation through vascular endothelial growth factor (VEGF) upregulation.

METHODS

Transgenic mice were generated via microinjection of a DNA construct containing the human VEGF165 (hVEGF) gene driven by a truncated mouse rhodopsin promoter. Mouse eyes were characterised clinically and histologically and ocular hVEGF levels assayed by ELISA.

RESULTS

One transgenic line expressing low hVEGF levels showed mild clinical changes such as focal fluorescein leakage, microaneurysms, venous tortuosity, capillary non-perfusion and minor neovascularisation, which remained stable up to 3 months postnatal. Histologically, there were some disturbance and thinning of inner and outer nuclear layers, with occasional focal areas of neovascularisation. By contrast, three other lines expressing high hVEGF levels presented with concomitantly severe phenotypes. In addition to the above, clinical features included extensive neovascularisation, haemorrhage, and retinal detachment; histologically, focal to extensive areas of neovascularisation associated with retinal folds, cell loss in the inner and outer nuclear layers, and partial retinal detachment were common.

CONCLUSIONS

The authors generated four hVEGF overexpressing transgenic mouse lines with phenotypes ranging from mild to severe neovascularisation. These models are a valuable research tool to study excess VEGF related molecular and cellular changes and provide additional opportunities to test anti-angiogenic therapies.

Genetic Risk of Rhegmatogenous Retinal Detachment

OBJECTIVE

To investigate the magnitude of the genetic risk of nonsyndromic rhegmatogenous retinal detachments (RRDs) in a familial aggregation study.

DESIGN

Two hundred three consecutive patients with RRD and 461 controls without RRD were ascertained at the Department of Ophthalmology of the University Medical Centre Nijmegen in Nijmegen, the Netherlands. Data on family composition, history of RRD, and presence of other risk factors in siblings and offspring were collected by means of a questionnaire. Diagnosis of RRD was confirmed by evaluation of medical records.

RESULTS

One hundred eighty-one patients (89.2% of those eligible) and 408 controls (88.5% of invited controls) with 1090 and 2345 relatives, respectively, were included in the analysis. Thirteen familial RRDs (1.2%) were diagnosed in 10 case probands and 9 RRDs (0.4%) in 8 control probands. Siblings and offspring of cases had a higher incidence of RRD independent of age, sex, and myopia. The cumulative lifetime risk of RRD was 7.7% for relatives of cases and 3.0% for relatives of controls, yielding a risk ratio of 2.6 (95% confidence interval, 1.1-6.2).

CONCLUSIONS

Familial occurrence of RRD is a risk factor for RRD. Genetic factors apart from myopia may explain the increased familial risk.

Phenotypic heterogeneity associated with a novel mutation (Gly112Glu) in the Norrie disease protein

PURPOSE

To determine the molecular pathology and clinical severity of two pedigrees with a history of early retinal detachment and peripheral retinal vascular abnormalities.

DESIGN

Longitudinal cohort study.

METHODS

A longitudinal clinical study and DNA analysis was performed on 49 family members of two pedigrees.

RESULTS

Nine individuals were found to be hemizygous for a mutation at codon 112 (Gly112Glu) of the Norrie disease protein (NDP) in one pedigree. Significant phenotypic heterogeneity was found. The proband presented with a unilateral subtotal retinal detachment at the age of 3 years, and subsequently developed a slowly progressive tractional retinal detachment involving the macula in the contralateral eye at the age of 4 years. One individual had only mild peripheral retinal pigmentary changes with normal vision at the age of 79 years. The remaining seven individuals had varying degrees of peripheral retinal vascular abnormalities and anterior segment findings. Seven affected members of a second pedigree affected by a previously reported mutation, Arg74Cys, also demonstrated wide ocular phenotypic variation.

CONCLUSION

A novel mutation (Gly112Glu), which represents the most carboxy located, NDP mutation reported, results in significant phenotypic heterogeneity. These data support the contention that the spectrum of ocular disease severity associated with these NDP mutations is broad. Use of terms that characterize this entity by phenotypic appearance, such as familial exudative vitreoretinopathy, do not adequately communicate the potential spectrum of severity of this disorder to affected or carrier family members.

A Novel Mutation ofCOL2A1Resulting in Dominantly Inherited Rhegmatogenous Retinal Detachment

PURPOSE

To determine the molecular defect in a family with autosomal dominant rhegmatogenous retinal detachment (DRRD), and to investigate missplicing as a possible phenotypic modifier of mutations in COL2A1.

METHODS

Clinical examination of the family and linkage analysis using markers flanking COL2A1 and COL11A1, the known loci for Stickler syndrome; mutation screening of COL2A1; construction of splicing reporter minigenes and transfection into cultured cells; and RT-PCR analysis of reporter specific transcripts.

RESULTS

A family with DRRD showed no systemic clinical signs (skeletal, orofacial, or auditory) usually associated with Stickler syndrome. Linkage analysis excluded COL11A1 as the disease locus but could not exclude COL2A1. Mutation screening of COL2A1 identified a novel G118R mutation in type II collagen. Transfection of minigenes carrying mutations associated with DRRD (G118R, R453X, and L467F) into cultured cells detected no missplicing of mRNA from mutant constructs.

CONCLUSIONS

Mutations outside the alternatively spliced exon 2 region of COL2A1 can also result in an ocular only phenotype. There was no evidence that missplicing modifies the phenotype of these mutations, suggesting that the minimal or absent systemic features demonstrated by the G118R and L467F mutations are the result of the biophysical changes imparted on the collagen molecule.

Genetic linkage of snowflake vitreoretinal degeneration to chromosome 2q36

PURPOSE

To identify the chromosomal location of the gene causing snowflake vitreoretinal degeneration (SVD), an autosomal dominant retinal degeneration characterized by small yellow-white dots in the retina, fibrillar anomaly of the vitreous humor, and retinal detachment.

METHODS

Clinical data were collected on 31 family members by history and examination. Thirteen family members underwent prospective examination. Genotyping was performed using microsatellite markers spaced at approximately 10 cM intervals. Two-point and multipoint linkage analysis was performed (FASTLINK version of the MLINK program and the VITESSE algorithm, both available at http://linkage.rockefeller.edu/soft/list.html). Direct DNA sequencing of amplified genomic DNA and mRNA was performed for candidate gene analysis.

RESULTS

The SVD locus was linked to markers in a region of chromosome 2q36 defined by D2S2158 and D2S2202, based on meiotic breakpoint mapping of affected individuals. A maximum two-point lod score of 5.5 was obtained with marker D2S172 at theta; = 0 within this region. Direct DNA sequencing of all 52 exons of the COL4A3 gene revealed no potentially pathogenic coding sequence variation or evidence for deletion.

CONCLUSIONS

The genetic locus for SVD lies in a 9 Mb region flanked by D2S2158 and D2S2202. Localization of SVD to a genomic region distinct from both Wagner disease and the Stickler syndromes indicates that SVD is a distinct genetic entity. The absence of coding sequence variation in the only collagen gene within the disease-region, suggests a novel pathogenesis for vitreoretinal degeneration. Snowflake vitreoretinal degeneration should be considered in the differential diagnosis of families with fibrillar anomaly of the vitreous.

X-LINKED RETINOSCHISIS IN THREE FEMALES FROM THE SAME FAMILY: A PHENOTYPE–GENOTYPE CORRELATION

PURPOSE

To describe the clinical findings and outcome for three homozygous females affected with X-linked retinoschisis (XLRS) in a large Colombian family with 26 affected males.

METHODS

Retrospective review of charts for females from a family with XLRS who underwent complete ophthalmologic examinations, ancillary tests, clinical genetic evaluation, and molecular studies.

RESULTS

Three female patients (6 eyes) with clinical findings of XLRS were identified. The patients' ages ranged from 10 to 37 years. Initial visual acuity was equal to or worse than 20/50 in 4 eyes (66%) of 2 patients. Four eyes (66%) were hyperopic. Intraocular pressure was normal in all eyes. Three eyes (50%) had cataracts, and vitreous veils were present in 3 (50%). The optic disk was pale in 6 eyes (100%). Foveal schisis was present in 6 eyes (100%). Peripheral retinal schisis was present in five eyes. A silvery gloss or tapetal-like retinal reflex or sheen was observed in 6 eyes (100%), and dendritic lines were found in 2 (33%). One eye had a retinal break, and one had a retinal detachment. Two eyes underwent cataract extraction; one patient underwent bilateral cryotherapy, one, laser treatment, and one, scleral buckling. Final visual acuity was 20/50 to 20/100 in 2 eyes and 20/200 to 20/400 in 4. Follow-up ranged from 7 to 22 years. Molecular analysis showed that all three female patients were homozygous for the allele 639delG of (on) the XRLS1 gene.

CONCLUSIONS

Compared with their affected male relatives, three females from a family with XLRS had similar ocular findings and a more severe course of disease. These findings are explained by the fact that these patients were homozygous for a mutation in the XLRS1 gene.

Criswick-Schepens-Syndrom ? Famili�re exsudative Vitreoretinopathie

BACKGROUND

Familial exudative vitreoretinopathy is a hereditary, bilaterally progressive formation of a vitreoretinal membrane. It usually occurs in full-term newborns without previous treatment with hyperbaric oxygen. In this report, we present six cases of this disease with various abnormalities of the posterior segment diagnosed in two Syrian families related by first degree of consanguinity.

DESIGN

A retrospective family analysis and presentation of cases.

CASE PRESENTATION

Six members of the two consanguineous families, aged between 3.5 and 13 years, who were systemically healthy, presented with a visual acuity ranging between light perception and 0.4 with bilateral fundus changes. The findings included: papillary, macular, and retinal temporal traction in 11 eyes, a retinal fold in 7 eyes, a fibrovascular mass in 11 eyes, vitreoretinal traction in 5 eyes, subretinal exudation in 2 eyes, pigmentary abnormalities in 2 eyes, temporal or total tractional retinal detachment in 2 eyes, and vitreous hemorrhage in 1 eye.

SUMMARY

Familial exudative vitreoretinopathy is characterized by fundus changes that resemble retinopathy of prematurity and must be differentiated from other diseases (e.g., Coats' disease, incontinentia pigmenti, persistent hyperplastic primary vitreous, and Norrie's disease).

Autosomal dominant rhegmatogenous retinal detachment--clinical appearance and surgical outcome

PURPOSE

To study the clinical appearance and surgical results of autosomal dominantly inherited rhegmatogenous retinal detachments (RRDs).

METHODS

After prospective examination of all but two family members, the medical records of 16 affected patients (21 eyes) of two families from the Netherlands with autosomal dominantly inherited RRD were retrospectively evaluated. Special attention was paid to the age at onset, the ocular morphology and the clinical appearance of the RRD. The type and number of the various surgical procedures were analyzed with respect to preoperative appearance of the RRD, postoperative results and final visual acuity.

RESULTS

The mean age at onset of RRD of affected individuals in families A and B was 37 +/- 18 years and 19 +/- 10 years, respectively. The mean ocular axial length in the two families was 24.7 mm and 26.7 mm. The mean number of retinal defects preoperatively found was 2.2 in family A and 7.1 in family B. Round, atrophic retinal holes predominated. Two of 21 affected eyes showed significant preoperative proliferative vitreoretinopathy. Pars plana vitrectomy was the primary procedure in 4 cases; extra ocular buckling was the initial procedure in 15 cases. One eye received scleral folding with diathermy as primary surgery. Redetachment following surgery occurred in 5 of 10 cases in family A and 4 of 10 eyes in family B. Anatomical success could be achieved in 9 of 10 and 8 of 10 eyes in families A and B, respectively.

CONCLUSIONS

In these families the prevalence of RRD is high. Most patients were affected at a relatively young age compared with non-genetically linked forms of RRD. Because of the low success rate of surgical intervention and, subsequently, the high number of operations necessary to achieve reattachment of the retina, the use of diagnostic genetic techniques to identify individuals at risk would be advisable. In these subjects measures to prevent RRD are an option, even when anatomical substrates of precursors of RRD are absent.

Knobloch syndrome: novel mutations in COL18A1, evidence for genetic heterogeneity, and a functionally impaired polymorphism in endostatin

Knobloch syndrome (KNO) is an autosomal recessive disorder characterized by high myopia, vitreoretinal degeneration with retinal detachment, and congenital encephalocele. Pathogenic mutations in the COL18A1 gene on 21q22.3 were recently identified in KNO families. Analysis of two unrelated KNO families from Hungary and New Zealand allowed us to confirm the involvement of COL18A1 in the pathogenesis of KNO and to demonstrate the existence of genetic heterogeneity. Two COL18A1 mutations were identified in the Hungarian family: a 1-bp insertion causing a frameshift and a premature in-frame stop codon and an amino acid substitution. This missense variant is located in a conserved amino acid of endostatin, a cleavage product of the carboxy-terminal domain of collagen alpha 1 XVIII. D1437N (D104N in endostatin) likely represents a pathogenic mutation, as we show that the endostatin N104 mutant is impaired in its affinity towards laminin. Linkage to the COL18A1 locus was excluded in the New Zealand family, providing evidence for the existence of a second KNO locus. We named the second unmapped locus for Knobloch syndrome KNO2. Mutation analysis excluded COL15A1, a member of the multiplexin collagen subfamily similar to COL18A1, as being responsible for KNO2.

A case of Kniest dysplasia with retinal detachment and the mutation analysis

PURPOSE

To report a case of Kniest dysplasia with retinal detachment associated with a novel type II collagen gene (COL2A1) mutation.

DESIGN

Interventional case report.

METHODS

DNA was isolated from peripheral lymphocytes, and mutational analysis was carried out using polymerase chain reaction and direct sequencing.

RESULTS

A 14-year-old Japanese boy was diagnosed with Kniest dysplasia, and ophthalmic examination revealed a retinal detachment in the right eye. He was successfully treated by vitrectomy and silicon oil injection, and his visual acuity improved from 0.01 to 0.22. DNA analysis of COL2A1 revealed a single base-pair substitution at position +5 of intron 20.

CONCLUSION

Vitrectomy and silicon oil injection were effective in reattaching the retinal detachment in a Kniest dysplasia patient. The genetic alteration found in this patient suggested that this prevented the normal splicing of COL2A1, resulting in an abnormal type II collagen product.

Autosomal dominant rhegmatogenous retinal detachment associated with an Arg453Ter mutation in the COL2A1 gene

PURPOSE

To investigate the clinical features and molecular causes of autosomal dominant rhegmatogenous retinal detachment (RRD) in two large families.

METHODS

Clinical examination and linkage analysis of both families using markers flanking the COL2A1 gene associated with Stickler syndrome type 1, the loci for Wagner disease/erosive vitreoretinopathy (5q14.3), high myopia (18p11.31 and 12q21-q23), and nonsyndromic congenital retinal nonattachment (10q21).

RESULTS

Fifteen individuals from family A and 12 individuals from family B showed RRD or retinal tears with minimal (family A) or no (family B) systemic characteristics of Stickler syndrome and no ocular features of Wagner disease or erosive vitreoretinopathy. The RRD cosegregated fully with a chromosomal region harboring the COL2A1 gene with maximum lod scores of 6.09 (family A) and 4.97 (family B). In family B, an Arg453Ter mutation was identified in exon 30 of the COL2A1 gene, that was previously described in a patient with classic Stickler syndrome. In family A, DNA sequence analysis revealed no mutation in the coding region and at the splice sites of the COL2A1 gene.

CONCLUSIONS

In two large families with RRD, linkage was found at the COL2A1 locus. In one of these families an Arg453Ter mutation was identified, which is surprising, because all predominantly ocular Stickler syndrome cases until now have been associated with protein-truncating mutations in exon 2, an exon subject to alternative splicing. In contrast, the Arg453Ter mutation and other protein-truncating mutations in the helical domain of COL2A1 have been associated until now with classic Stickler syndrome.