Search

Pre-mRNA splicing factors play a fundamental role in regulating transcript diversity both temporally and spatially. Genetic defects in several spliceosome components have been linked to a set of non-overlapping spliceosomopathy phenotypes in humans, among which skeletal developmental defects and non-syndromic retinitis pigmentosa (RP) are frequent findings. Here we report that defects in spliceosome-associated protein CWC27 are associated with a spectrum of disease phenotypes ranging from isolated RP to severe syndromic forms. By whole-exome sequencing, recessive protein-truncating mutations in CWC27 were found in seven unrelated families that show a range of clinical phenotypes, including retinal degeneration, brachydactyly, craniofacial abnormalities, short stature, and neurological defects. Remarkably, variable expressivity of the human phenotype can be recapitulated in Cwc27 mutant mouse models, with significant embryonic lethality and severe phenotypes in the complete knockout mice while mice with a partial loss-of-function allele mimic the isolated retinal degeneration phenotype. Our study describes a retinal dystrophy-related phenotype spectrum as well as its genetic etiology and highlights the complexity of the spliceosomal gene network., (Copyright © 2017 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.)

NR2E3 encodes the photoreceptor-specific nuclear hormone receptor that acts as a repressor of cone-specific gene expression in rod photoreceptors, and as an activator of several rod-specific genes. Recessive variants located in the ligand-binding domain (LBD) of NR2E3 cause enhanced short wavelength sensitive- (S-) cone syndrome (ESCS), a retinal degeneration characterized by an excess of S-cones and non-functional rods. We analyzed the dimerization properties of NR2E3 and the effect of disease-causing LBD missense variants by bioluminescence resonance energy transfer (BRET(2) ) protein interaction assays. Homodimerization was not affected in presence of p.A256V, p.R039G, p.R311Q, and p.R334G variants, but abolished in presence of p.L263P, p.L336P, p.L353V, p.R385P, and p.M407K variants. Homology modeling predicted structural changes induced by NR2E3 LBD variants. NR2E3 LBD variants did not affect interaction with CRX, but with NRL and rev-erbα/NR1D1. CRX and NRL heterodimerized more efficiently together, than did either with NR2E3. NR2E3 did not heterodimerize with TLX/NR2E1 and RXRα/NR2C1. The identification of a new compound heterozygous patient with detectable rod function, who expressed solely the p.A256V variant protein, suggests a correlation between LBD variants able to form functional NR2E3 dimers and atypical mild forms of ESCS with residual rod function., (© 2015 WILEY PERIODICALS, INC.)

Purpose: To analyze in vivo the function of chicken acidic leucine-rich epidermal growth factor-like domain containing brain protein/Neuroglycan C (gene symbol: Cspg5) during retinal degeneration in the Rpe65⁻/⁻ mouse model of Leber congenital amaurosis., Methods: We resorted to mice with targeted deletions in the Cspg5 and retinal pigment epithelium protein of 65 kDa (Rpe65) genes (Cspg5⁻/⁻/Rpe65⁻/⁻). Cone degeneration was assessed with cone-specific peanut agglutinin staining. Transcriptional expression of rhodopsin (Rho), S-opsin (Opn1sw), M-opsin (Opn1mw), rod transducin α subunit (Gnat1), and cone transducin α subunit (Gnat2) genes was assessed with quantitative PCR from 2 weeks to 12 months. The retinal pigment epithelium (RPE) was analyzed at P14 with immunodetection of the retinol-binding protein membrane receptor Stra6., Results: No differences in the progression of retinal degeneration were observed between the Rpe65⁻/⁻ and Cspg5⁻/⁻/Rpe65⁻/⁻ mice. No retinal phenotype was detected in the late postnatal and adult Cspg5⁻/⁻ mice, when compared to the wild-type mice., Conclusions: Despite the previously reported upregulation of Cspg5 during retinal degeneration in Rpe65⁻/⁻ mice, no protective effect or any involvement of Cspg5 in disease progression was identified.

Purpose: To investigate the role of the myocyte enhancer factor 2 (Mef2) transcription factor family in retinal diseases, Mef2c expression was assessed during retinal degeneration in the Rpe65(-/-) mouse model of Leber's congenital amaurosis (LCA). Mef2c-dependent expression of photoreceptor-specific genes was further addressed., Methods: Expression of Mef2 members was analyzed by oligonucleotide microarray, quantitative PCR (qPCR), and in situ hybridization. Mef2c-dependent transcriptional activity was assayed by luciferase assay in HEK293T cells., Results: Mef2c was the only Mef2 member markedly downregulated during retinal degeneration in Rpe65(-/-) mice. Mef2c mRNA level was decreased by more than 2-fold at 2 and 4 months and by 3.5-fold at 6 months in retinas of Rpe65(-/-) mice. Downregulation of Mef2c at the protein level was confirmed in Rpe65(-/-) retinas. The decrease in Mef2c mRNA levels in the developing Rpe65(-/-) retinas from postnatal day (P) 13 onward was concomitant with the decreased expression of the rod-specific transcription factors Nrl and Nr2e3. Nrl was further shown to drive Mef2c transcriptional activity, supporting a physiological role for Mef2c in the retina. In addition, Mef2c appeared to act as a transcriptional repressor of its own expression and the expression of the retina-specific retinal G-protein coupled receptor (Rgr), rhodopsin, and M-opsin genes., Conclusions: These findings highlight the early altered regulation of the rod-specific transcriptional network in Rpe65-related disease. They also indicate that Mef2c may act as a novel transcription factor involved in the development and the maintenance of photoreceptor cells.

NR2E3, a photoreceptor-specific nuclear receptor (PNR), represses cone-specific genes and activates several rod-specific genes. In humans, mutations in NR2E3 have been associated with the recessively-inherited enhanced short-wavelength sensitive S-cone syndrome (ESCS) and, recently, with autosomal dominant (ad) retinitis pigmentosa (RP) (adRP). In the present work, we describe two additional families affected by adRP that carry a heterozygous c.166G>A (p.G56R) mutation in the NR2E3 gene. Functional analysis determined the dominant negative activity of the p.G56R mutant protein as the molecular mechanism of adRP. Interestingly, in one pedigree, the most common causal variant for ESCS (p.R311Q) cosegregated with the adRP-linked p.G56R mutation, and the compound heterozygotes exhibited an ESCS-like phenotype, which in 1 of the 2 cases was strikingly "milder" than the patients carrying the p.G56R mutation alone. Impaired repression of cone-specific genes by the corepressors atrophin-1 (dentatorubral-pallidoluysian atrophy [DRPLA] gene product) and atrophin-2 (arginine-glutamic acid dipeptide repeat [RERE] protein) appeared to be a molecular mechanism mediating the beneficial effect of the p.R311Q mutation. Finally, the functional dominance of the p.R311Q variant to the p.G56R mutation is discussed., (2008 Wiley-Liss, Inc.)

Purpose: Despite ubiquitous expression of the keratoepithelin (KE) protein encoded by the transforming growth factor beta induced/beta induced gene human clone 3 (TGFBI/BIGH3) gene, corneal dystrophies are restricted to the cornea, and no other tissues are affected. We investigated the role of TGFBI/BIGH3 in Groenouw corneal dystrophies by generating transgenic mice overexpressing TGFBI/BIGH3 containing the R555W mutation., Methods: Transgenic animals expressing the Groenouw mutation of human TGFBI/BIGH3 were generated using lentiviral vectors. The line expressed TGFBI/BIGH3 containing the R555W mutation under the control of the phosphoglycerate kinase (PGK) promoter. Expression of the transgene was monitored by Southern and western blotting and by RT-PCR. Electroretinogram analysis was performed and four mice were subjected to complete necroscopy., Results: Transgene expression was observed in different organs although without specific expression in the cornea. The overall morphology of the transgenic animals was not severely affected by KE overexpression. However, we observed an age-dependent retinal degeneration both functionally and histologically. Female-specific follicular hyperplasia in the spleen and increased levels of lipofuscin in the adrenal gland were also seen in transgenic animals., Conclusions: Cellular degeneration in the retina of transgenic animals suggest that perturbation of the transforming growth factor beta (TGFbeta) family regulation may affect photoreceptor survival and may induce possible accelerated aging in several tissues. No corneal phenotype could be observed, probably due to the lack of transgene expression in this tissue.

Purpose: An increased mRNA expression of the genes coding for the extracellular matrix proteins neuroglycan C (NGC), interphotoreceptor matrix proteoglycan 2 (IMPG2), and CD44 antigen (CD44) has been observed during retinal degeneration in mice with a targeted disruption of the Rpe65 gene (Rpe65-/- mouse). To validate these data, we analyzed this differential expression in more detail by characterizing retinal NGC mRNA isoform and protein expression during disease progression., Methods: Retinas from C57/Bl6 wild-type and Rpe65-/- mice, ranging 2 to 18 months of age, were used. NGC, IMPG2, and CD44 mRNA expression was assessed by oligonucleotide microarray, quantitative PCR, and in situ hybridization. Retinal NGC protein expression was analyzed by western blot and immunohistochemistry., Results: As measured by quantitative PCR, mRNA expression of NGC and CD44 was induced by about 2 fold to 3 fold at all time points in Rpe65-/- retinas, whereas initially 4 fold elevated IMPG2 mRNA levels progressively declined. NGC and IMPG2 mRNAs were expressed in the ganglion cell layer, the inner nuclear layer, and at the outer limiting membrane. NGC mRNA was also detected in retinal pigment epithelium cells (RPE), where its mRNA expression was not induced during retinal degeneration. NGC-I was the major isoform detected in the retina and the RPE, whereas NGC-III was barely detected and NGC-II could not be assessed. NGC protein expression was at its highest levels on the apical membrane of the RPE. NGC protein levels were induced in retinas from 2- and 4-month-old Rpe65-/- mice, and an increased amount of the activity-cleaved NGC ectodomain containing an epidermal growth factor (EGF)-like domain was detected., Conclusions: During retinal degeneration in Rpe65-/- mice, NGC expression is induced in the neural retina, but not in the RPE, where NGC is expressed at highest levels.

Purpose: To report a large, consanguineous Algerian family affected with Leber congenital amaurosis (LCA) or early-onset retinal degeneration (EORD)., Methods: All accessible family members underwent a complete ophthalmic examination, and blood was obtained for DNA extraction. Homozygosity mapping was performed with markers flanking 12 loci associated with LCA. The 15 exons of TULP1 were sequenced., Results: Seven of 30 examined family members were affected, including five with EORD and two with LCA. All patients had nystagmus, hemeralopia, mild myopia, and low visual acuity without photophobia. Fundus features were variable among EORD patients: typical spicular retinitis pigmentosa or clumped pigmented retinopathy with age-dependent macular involvement. A salt-and-pepper retinopathy with midperipheral retinal pigment epithelium (RPE) atrophy was present in the older patients with LCA, whereas the retina appeared virtually normal in the younger ones. Both scotopic and photopic electroretinograms were nondetectable. Fundus imaging revealed a perifoveal ring of increased fundus autofluorescence (FAF) in the proband, and optical coherence tomography disclosed a thinned retina, mainly due to photoreceptor loss. Linkage analysis identified a region of homozygosity on chromosome 6, region p21.3, and mutation screening revealed a novel 6-base in-frame duplication, in the TULP1 gene., Conclusions: Mutation in the TULP1 gene is a rare cause of LCA/EORD, with only 14 mutations reported so far. The observed intrafamilial phenotypic variability could be attributed to disease progression or possibly modifier alleles. This study provides the first description of FAF and quantitative reflectivity profiles in TULP1-related retinopathy.

Purpose: To identify the genetic defect, and to phenotype, three consanguineous Tunisian families presenting with early-onset retinal degeneration (EORD)., Methods: All accessible family members were included. They underwent blood sampling and ophthalmological examination including, when possible, full-field ERG and pupillometry. A genome-wide linkage analysis was initiated. Mutation analysis of the RPE65 gene within the linked interval was performed by bi-directional sequencing., Results: Eleven out of 53 examined members were clinically affected with an EORD. Linkage analysis revealed a maximal lod score of 4.02 (theta=0.1) for the marker D1S207 on 1p31. Mutational screening of the RPE65 gene identified a homozygous R91W mutation co-segregating with the disease in all affected individuals. Eleven homozygotes had nystagmus and acuities ranging from CF to NLP. Two retinal patterns were identified: pattern 1 presented mid-peripheral deep white dot deposits and virtually no clumped pigmentation, whereas pattern 2 showed mid-peripheral pigmented clumps without any white deposits. Homozygotes had no detectable full-field ERG and an abnormal pupillary light reflex. Eleven heterozygotes had normal visual function., Conclusion: We identified and characterised an endemic form of early onset rod-cone dystrophy in a consanguineous population from northeastern Tunisia, due to the prevalence of a single RPE65 mutation. Two funduscopic patterns were identified: white dot deposits in earlier stages and clumped pigment in later stages.

Bietti crystalline corneoretinal dystrophy (BCD) is an autosomal recessive retinal dystrophy characterized by multiple glistening intraretinal crystals scattered over the fundus, a characteristic degeneration of the retina, and sclerosis of the choroidal vessels, ultimately resulting in progressive night blindness and constriction of the visual field. The BCD region of chromosome 4q35.1 was refined to an interval flanked centromerically by D4S2924 by linkage and haplotype analysis; mutations were found in the novel CYP450 family member CYP4V2 in 23 of 25 unrelated patients with BCD tested. The CYP4V2 gene, transcribed from 11 exons spanning 19 kb, is expressed widely. Homology to other CYP450 proteins suggests that CYP4V2 may have a role in fatty acid and steroid metabolism, consistent with biochemical studies of patients with BCD.

We report the molecular basis of the largest Tunisian cohort with inherited retinal dystrophies (IRD) reported to date, identify disease-causing pathogenic variants and describe genotype–phenotype correlations. A subset of 26 families from a cohort of 73 families with clinical diagnosis of autosomal recessive IRD (AR-IRD) excluding Usher syndrome was analyzed by whole exome sequencing and autozygosity mapping. Causative pathogenic variants were identified in 50 families (68.4%), 42% of which were novel. The most prevalent pathogenic variants were observed in ABCA4 (14%) and RPE65, CRB1 and CERKL (8% each). 26 variants (8 novel and 18 known) in 19 genes were identified in 26 families (14 missense substitutions, 5 deletions, 4 nonsense pathogenic variants and 3 splice site variants), with further allelic heterogeneity arising from different pathogenic variants in the same gene. The most common phenotype in our cohort is retinitis pigmentosa (23%) and cone rod dystrophy (23%) followed by Leber congenital amaurosis (19.2%). We report the association of new disease phenotypes. This research was carried out in Tunisian patients with IRD in order to delineate the genetic population architecture. [ABSTRACT FROM AUTHOR]

Background: We present a macular dystrophy of differing severity in a single kindred caused by a heterozygous nonsense mutation in CRX. Case report: A 21-year-old Caucasian male from a Swiss family was investigated for decreasing central visual acuity associated with dischromatopsia. Clinical examination revealed posterior pole atrophy, including the maculopapillary bundle. Multimodal imaging, including autofluorescence, showed a hyperautofluorescent paramacular ring in both eyes. Genetic analysis identified a c.313C>T, p.Q105* nonsense mutation in CRX. The same mutation was identified in his father and uncle. Both of them showed signs of the disease, however with different severity. Conclusion: We describe an intrafamilial variable expressivity of a CRX mutation causing an isolated macular dystrophy. [ABSTRACT FROM AUTHOR]

To assess the progression of Stargardt (STGD) disease over nine years in two branches of a large consanguineous Tunisian family. Initially, different phenotypes were observed with clinical intra- and interfamilial variations. At presentation, four different retinal phenotypes were observed. In phenotype 1, bull’s eye maculopathy and slight alteration of photopic responses in full-field electroretinography were observed in the youngest child. In phenotype 2, macular atrophy and yellow white were observed in two brothers. In phenotype 3, diffuse macular, peripapillary, and peripheral RPE atrophy and hyperfluorescent dots were observed in two sisters. In phenotype 4, Stargardt disease-fundus flavimaculatus phenotype was observed in two cousins with later age of onset. After a progression of 9 years, all seven patients displayed the same phenotype 3 with advanced stage STGD and diffuse atrophy. WES and MLPA identified two ABCA4 mutations M1: c.[(?_4635)_(5714+?)dup; (?_6148)_(6479_+?) del] and M2: c.[2041C>T], p.[R681∗]. In one branch, the three affected patients had M1/M1 causal mutations and in the other branch the two affected patients had M1/M2 causal mutations. After 9-year follow-up, all patients showed the same phenotypic evolution, confirming the progressive nature of the disease. Genetic variations in the two branches made no difference to similar end-stage disease. [ABSTRACT FROM AUTHOR]

Purpose To evaluate the relationship between the peripapillary metabolic alterations [retinal vessel Oximetry ( RO)] and the structural findings [retinal vessel diameter and retinal nerve fibre layer thickness ( RNFL)] in patients with inherited retinal dystrophies ( IRD). Methods Patients with IRD [24 patients with rod-cone dystrophy ( RCD), 15 patients with cone-rod dystrophy, 13 patients with inherited maculopathy] and 18 age-matched controls, who underwent RO imaging and spectral domain optical coherence tomography, were included. The average and quadrant oxygen saturation in all four major peripapillary retinal arterioles (A- SO2) and venules (V- SO2) were measured, and their difference (A-V SO2) was calculated. The corresponding retinal vessel diameter of these arterioles (D-A) and venules (D-V) was measured. The data were compared to the peripapillary RNFL thickness within the IRD subgroups and to the data obtained in the controls. Results In general, patients with IRD had higher average V- SO2 values when compared to controls (p ≤ 0.029). Rod-cone dystrophy (RCD) patients differed from controls, but also from patients with other IRDs, when the average and quadrant oxygen saturation values (A- SO2 and V- SO2) were evaluated (p ≤ 0.026). Within the RCD group, the correlations of RNFL thickness to V- SO2, A-V SO2, D-A and D-V were significant (p ≤ 0.030), thus indicating a different relationship between the RNFL thickness and the examined parameters, when compared to the other groups. Conclusion It becomes evident from our combined metabolic-structural approach that a prediction model, to identify which individual is at risk of developing a photoreceptor degeneration of RCD type, can be proposed. It will take into account the peripapillary retinal oxygen saturation, the retinal vessel diameter and the RNFL thickness values. [ABSTRACT FROM AUTHOR]

ABSTRACT NR2E3 encodes the photoreceptor-specific nuclear hormone receptor that acts as a repressor of cone-specific gene expression in rod photoreceptors, and as an activator of several rod-specific genes. Recessive variants located in the ligand-binding domain (LBD) of NR2E3 cause enhanced short wavelength sensitive- (S-) cone syndrome (ESCS), a retinal degeneration characterized by an excess of S-cones and non-functional rods. We analyzed the dimerization properties of NR2E3 and the effect of disease-causing LBD missense variants by bioluminescence resonance energy transfer (BRET2) protein interaction assays. Homodimerization was not affected in presence of p.A256V, p.R039G, p.R311Q, and p.R334G variants, but abolished in presence of p.L263P, p.L336P, p.L353V, p.R385P, and p.M407K variants. Homology modeling predicted structural changes induced by NR2E3 LBD variants. NR2E3 LBD variants did not affect interaction with CRX, but with NRL and rev-erbα/NR1D1. CRX and NRL heterodimerized more efficiently together, than did either with NR2E3. NR2E3 did not heterodimerize with TLX/NR2E1 and RXRα/NR2C1. The identification of a new compound heterozygous patient with detectable rod function, who expressed solely the p.A256V variant protein, suggests a correlation between LBD variants able to form functional NR2E3 dimers and atypical mild forms of ESCS with residual rod function. [ABSTRACT FROM AUTHOR]

Background: Glucose is the most important metabolic substrate of the retina and maintenance of normoglycemia is an essential challenge for diabetic patients. Glycemic excursions could lead to cardiovascular disease, nephropathy, neuropathy and retinopathy. A vast body of literature exists on hyperglycemia namely in the field of diabetic retinopathy, but very little is known about the deleterious effect of hypoglycemia. Therefore, we decided to study the role of acute hypoglycemia in mouse retina. Methodology/Principal Findings: To test effects of hypoglycemia, we performed a 5-hour hyperinsulinemic/hypoglycemic clamp; to exclude an effect of insulin, we made a hyperinsulinemic/euglycemic clamp as control. We then isolated retinas from each group at different time-points after the clamp to analyze cells apoptosis and genes regulation. In parallel, we used 661W photoreceptor cells to confirm in vivo results. We showed herein that hypoglycemia induced retinal cell death in mouse via caspase 3 activation. We then tested the mRNA expression of glutathione transferase omega 1 (Gsto1) and glutathione peroxidase 3 (Gpx3), two genes involved in glutathione (GSH) homeostasis. The expression of both genes was up-regulated by low glucose, leading to a decrease of reduced glutathione (GSH). In vitro experiments confirmed the lowglucose induction of 661W cell death via superoxide production and activation of caspase 3, which was concomitant with a decrease of GSH content. Moreover, decrease of GSH content by inhibition with buthionine sulphoximine (BSO) at high glucose induced apoptosis, while complementation with extracellular glutathione ethyl ester (GSHee) at low glucose restored GSH level and reduced apoptosis. Conclusions/Significance: We showed, for the first time, that acute insulin-induced hypoglycemia leads to caspase 3- dependant retinal cell death with a predominant role of GSH content. [ABSTRACT FROM AUTHOR]

Pathogenesis in the Rpe65-/- mouse model of Leber's congenital amaurosis (LCA) is characterized by a slow and progressive degeneration of the rod photoreceptors. On the opposite, cones degenerate rapidly at early ages. Retinal degeneration in Rpe65-/- mice, showing a null mutation in the gene encoding the retinal pigment epithelium 65-kDa protein (Rpe65), was previously reported to depend on continuous activation of a residual transduction cascade by unliganded opsin. However, the mechanisms of apoptotic signals triggered by abnormal phototransduction remain elusive. We previously reported that activation of a Bcl-2-dependent pathway was associated with apoptosis of rod photoreceptors in Rpe65-/- mice during the course of the disease. In this study we first assessed whether activation of Bcl-2-mediated apoptotic pathway was dependent on constitutive activation of the visual cascade through opsin apoprotein. We then challenged the direct role of pro-apoptotic Bax protein in triggering apoptosis of rod and cone photoreceptors. Quantitative PCR analysis showed that increased expression of pro-apoptotic Bax and decreased level of anti-apoptotic Bcl-2 were restored in Rpe65-/-/Gnat1-/- mice lacking the Gnat1 gene encoding rod transducin. Moreover, photoreceptor apoptosis was prevented as assessed by TUNEL assay. These data indicate that abnormal activity of opsin apoprotein induces retinal cell apoptosis through the Bcl-2-mediated pathway. Following immunohistological and real-time PCR analyses, we further observed that decreased expression of rod genes in Rpe65-deficient mice was rescued in Rpe65-/-/Bax-/- mice. Histological and TUNEL studies confirmed that rod cell demise and apoptosis in diseased Rpe65-/- mice were dependent on Bax-induced pathway. Surprisingly, early loss of cones was not prevented in Rpe65-/-/Bax-/- mice, indicating that proapoptotic Bax was not involved in the pathogenesis of cone cell death in Rpe65-deficient mice. This is the first report, to our knowledge, that a single genetic mutation can trigger two independent apoptotic pathways in rod and cone photoreceptors in Rpe65-dependent LCA disease. These results highlight the necessity to investigate and understand the specific death signaling pathways committed in rods and cones to develop effective therapeutic approaches to treat RP diseases. [ABSTRACT FROM AUTHOR]

Francois-Neetens fleck (mouchetée) corneal dystrophy is an autosomal dominant corneal dystrophy characterized by scattered small white flecks occurring at all levels of the corneal stroma. We report linkage of the CFD locus to D2S2289 (Zmax=4.46, θ=0), D2S325 (Zmax=3.28, θ=0), D2S317 (Zmax=3.1, θ=0), D2S143 (Zmax=3.8, θ=0.03), and D2S2382 (Zmax=5.0, θ=0) on chromosome 2q35. Multipoint analysis confirmed linkage to the region between D2S117 and D2S126 with a maximum multipoint lod score of 5.0 located midway between D2S2289 and D2S325. Analysis of CFD in these same families assuming a 90% penetrance increased the maximum lod score to 6.28 at D2S157. [ABSTRACT FROM AUTHOR]

Examines the relation of aberrant accumulation of EFEMP1 and drusen formation in Malattia Leventinese and age-related macular degeneration. Expression of recombinant genes; Synthesis of antibodies; Application of immunohistochemistry and immunofluorescence staining.

Objectives: To investigate the role of 2 specific alleles of the Stargardt disease gene (ABCA4) in the pathogenesis of age-related macular degeneration (AMD). Secondary objectives were to investigate differences in frequency of the G1961E allele in selected ethnic groups as well as to examine the segregation of both G1961E and D2177N alleles in 5 multiplex families with AMD. Methods: Five hundred forty-four patients with AMD and 689 controls were ascertained from 3 continents. Blood samples from 62 normal individuals of Somalian ancestry were also obtained. Participants were screened for the presence of these ABCA4 alleles with a combination of restriction digestion and single-strand conformation polymorphism analysis of polymerase chain reaction amplification products. Detected alleles were confirmed by DNA sequencing. The number of subjects exhibiting the G1961E or D2177N variants were compared between AMD and control groups using a 2-tailed Fisher exact test. Results: There was no significant difference (P>. 1) in the frequency of the G1961E and D2177N alleles in patients with AMD (2.2%) vs controls (1.0%). In contrast, there was a significant difference (P<.001) in the frequency of the G1961E alleles between normal individuals of Somali ancestry (11.3%) and normal individuals from other populations (0.4%). There was no evidence of cosegregation of these alleles and the AMD phenotype in the 5 multiplex families with AMD examined. These two ABCA4 alleles were slightly more frequent in patients with AMD with choroidal neovascularization (2.7%) than those without this complication (2.5%). Conclusions: Somali ancestry is more than 100 times more strongly associated with presence of the G1961E allele than the AMD phenotype. This study did not find any statistically significant evidence for involvement of the G1961E or D2177N alleles of the ABCA4 gene in AMD. Clinical Relevance: The ABCA4 gene is definitively involved in the pathogenesis of Stargardt disease and... [ABSTRACT FROM AUTHOR]

Malattia Leventinese (ML) and Doyne honeycomb retinal dystrophy (DHRD) refer to two autosomal dominant diseases characterized by yellow-white deposits known as drusen that accumulate beneath the retinal pigment epithelium (RPE). Both loci were mapped to chromosome 2p16-21 (Refs 5,6) and this genetic interval has been subsequently narrowed. The importance of these diseases is due in large part to their close phenotypic similarity to age-related macular degeneration (AMD), a disorder with a strong genetic component that accounts for approximately 50% of registered blindness in the Western world. Just as in ML and DHRD, the early hallmark of AMD is the presence of drusen. Here we use a combination of positional and candidate gene methods to identify a single non-conservative mutation (Arg345Trp) in the gene EFEMP1 (for EGF-containing fibrillin-like extracellular matrix protein 1) in all families studied. This change was not present in 477 control individuals or in 494 patients with age-related macular degeneration. Identification of this mutation may aid in the development of an animal model for drusen, as well as in the identification of other genes involved in human macular degeneration. [ABSTRACT FROM AUTHOR]

Cone-rod dystrophies are inherited dystrophies of the retina characterized by the accumulation of deposits mainly localized to the cone-rich macular region of the eye. Dystrophy can be limited to the retina or be part of a syndrome. Unlike nonsyndromic cone-rod dystrophies, syndromic cone-rod dystrophies are genetically heterogeneous with mutations in genes encoding structural, cell-adhesion, and transporter proteins. Using a genome-wide single-nucleotide polymorphism (SNP) haplotype analysis to fine map the locus and a gene- candidate approach, we identified homozygous mutations in the ancient conserved domain protein 4 gene (CNNM4) that either generate a truncated protein or occur in highly conserved regions of the protein. Given that CNNM4 is implicated in metal ion transport, cone-rod dystrophy and amelogenesis imperfecta may originate from abnormal ion homeostasis. [ABSTRACT FROM AUTHOR]

François­Neetens fleck corneal dystrophy (CFD) is a rare, autosomal dominant corneal dystrophy characterized by numerous small white flecks scattered in all layers of the stroma. Linkage analysis localized CFD to a 24-cM (18-Mb) interval of chromosome 2q35 flanked by D2S2289 and D2S126 and containing PIP5K3. PIP5K3 is a member of the phosphoinositide 3-kinase family and regulates the sorting and traffic of peripheral endosomes that contain lysosomally directed fluid phase cargo, by controlling the morphogenesis and function of multivesicular bodies. Sequencing analysis disclosed missense, frameshift, and/or protein-truncating mutations in 8 of 10 families with CFD that were studied, including 2256delA, 2274delCT, 2709C↵T (R851X), 3120C↵T (Q988X), IVS19-1G↵C, 3246G↵T (E1030X), 3270C↵T (R1038X), and 3466A↵G (K1103R). The histological and clinical characteristics of patients with CFD are consistent with biochemical studies of PIP5K3 that indicate a role in endosomal sorting. [ABSTRACT FROM AUTHOR]

Purpose: To describe new affected individuals of Franceschetti''s original pedigree of hereditary recurrent erosion and to classify a unique entity called Franceschetti corneal dystrophy. Design: Observational case series. Methods: Slit-lamp examination of 10 affected individuals was conducted. Biomicroscopic examinations were supplemented by peripheral corneal biopsy in 1 affected patient with corneal haze. Tissue was processed for light and electron microscopy and immunohistochemistry was performed. DNA analysis was carried out in 12 affected and 3 nonaffected family members. Results: All affected individuals suffered from severe ocular pain in the first decade of life, attributable to recurrent corneal erosions. Six adult patients developed bilateral diffuse subepithelial opacifications in the central and paracentral cornea. The remaining 4 affected individuals had clear corneas in the pain-free stage of the disorder. Histologic and immunohistochemical examination of the peripheral cornea in a single patient showed a subepithelial, avascular pannus. There was negative staining with Congo red. DNA analysis excluded mutations in the transforming growth factor beta–induced (TGFBI) gene and in the tumor-associated calcium signal transducer 2 (TACSTD2) gene. Conclusion: We have extended the pedigree of Franceschetti corneal dystrophy and elaborated its natural history on the basis of clinical examinations. A distinctive feature is the appearance of subepithelial opacities in adult life, accompanied by a decreased frequency of recurrent erosion attacks. Its clinical features appear to distinguish it from most other forms of dominantly inherited recurrent corneal erosion reported in the literature. [Copyright &y& Elsevier]