Anand Swaroop

National Institutes of Health, Maryland, United States

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Publications (264)1798.02 Total impact

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    ABSTRACT: Neurodegenerative diseases affecting the macula constitute a major cause of incurable vision loss and exhibit considerable clinical and genetic heterogeneity, from early-onset monogenic disease to multifactorial late-onset age-related macular degeneration (AMD). As part of our continued efforts to define genetic causes of macular degeneration, we performed whole exome sequencing in four individuals of a two-generation family with autosomal dominant maculopathy and identified a rare variant p.Glu1144Lys in Fibrillin 2 (FBN2), a glycoprotein of the elastin-rich extracellular matrix (ECM). Sanger sequencing validated the segregation of this variant in the complete pedigree, including two additional affected and one unaffected individual. Sequencing of 192 maculopathy patients revealed additional rare variants, predicted to disrupt FBN2 function. We then undertook additional studies to explore the relationship of FBN2 to macular disease. We show that FBN2 localizes to Bruch's membrane and its expression appears to be reduced in aging and AMD eyes, prompting us to examine its relationship with AMD. We detect suggestive association of a common FBN2 non-synonymous variant, rs154001 (p.Val965Ile) with AMD in 10,337 cases and 11,174 controls (OR=1.10; p-value=3.79×10(-5)). Thus, it appears that rare and common variants in a single gene - FBN2 - can contribute to Mendelian and complex forms of macular degeneration. Our studies provide genetic evidence for a key role of elastin microfibers and Bruch's membrane in maintaining blood-retina homeostasis and establish the importance of studying orphan diseases for understanding more common clinical phenotypes.
    Human Molecular Genetics 06/2014; · 7.69 Impact Factor
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    ABSTRACT: Genetic and genomic studies have enhanced our understanding of complex neurodegenerative diseases that exert a devastating impact on individuals and society. One such disease, age-related macular degeneration (AMD), is a major cause of progressive and debilitating visual impairment. Since the pioneering discovery in 2005 of complement factor H (CFH) as a major AMD susceptibility gene, extensive investigations have confirmed 19 additional genetic risk loci, and more are anticipated. In addition to common variants identified by now-conventional genome-wide association studies, targeted genomic sequencing and exome-chip analyses are uncovering rare variant alleles of high impact. Here, we provide a critical review of the ongoing genetic studies and of common and rare risk variants at a total of 20 susceptibility loci, which together explain 40-60% of the disease heritability but provide limited power for diagnostic testing of disease risk. Identification of these susceptibility loci has begun to untangle the complex biological pathways underlying AMD pathophysiology, pointing to new testable paradigms for treatment. Expected final online publication date for the Annual Review of Genomics and Human Genetics Volume 15 is September 01, 2014. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
    Annual review of genomics and human genetics 04/2014; · 11.57 Impact Factor
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    ABSTRACT: The Maf-family leucine zipper transcription factor NRL is essential for rod photoreceptor development and functional maintenance in the mammalian retina. Mutations in NRL are associated with human retinopathies, and loss of Nrl in mice leads to a cone-only retina with complete absence of rods. Among the highly down-regulated genes in the Nrl(-/-) retina, we identified receptor expression enhancing protein 6 (Reep6), which encodes a member of a family of proteins involved in shaping of membrane tubules and transport of G-protein coupled receptors. Here, we demonstrate the expression of a novel Reep6 isoform (termed Reep6.1) in the retina by exon-specific Taqman assay and rapid analysis of cDNA ends (5'-RACE). The REEP6.1 protein includes 27 additional amino acids encoded by exon 5 and is specifically expressed in rod photoreceptors of developing and mature retina. Chromatin immunoprecipitation assay identified NRL binding within the Reep6 intron 1. Reporter assays in cultured cells and transfections in retinal explants mapped an intronic enhancer sequence that mediated NRL-directed Reep6.1 expression. We also demonstrate that knockdown of Reep6 in mouse and zebrafish resulted in death of retinal cells. Our studies implicate REEP6.1 as a key functional target of an NRL-centered transcriptional regulatory network in rod photoreceptors.
    Human Molecular Genetics 04/2014; · 7.69 Impact Factor
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    ABSTRACT: Estimating individual ancestry is important in genetic association studies where population structure leads to false positive signals, although assigning ancestry remains challenging with targeted sequence data. We propose a new method for the accurate estimation of individual genetic ancestry, based on direct analysis of off-target sequence reads, and implement our method in the publicly available LASER software. We validate the method using simulated and empirical data and show that the method can accurately infer worldwide continental ancestry when used with sequencing data sets with whole-genome shotgun coverage as low as 0.001×. For estimates of fine-scale ancestry within Europe, the method performs well with coverage of 0.1×. On an even finer scale, the method improves discrimination between exome-sequenced study participants originating from different provinces within Finland. Finally, we show that our method can be used to improve case-control matching in genetic association studies and to reduce the risk of spurious findings due to population structure.
    Nature Genetics 03/2014; · 35.21 Impact Factor
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    ABSTRACT: Leber congenital amaurosis (LCA) encompasses a set of early-onset blinding diseases that are characterized by vision loss, involuntary eye movement, and nonrecordable electroretinogram (ERG). At least 19 genes are associated with LCA, which is typically recessive; however, mutations in homeodomain transcription factor CRX lead to an autosomal dominant form of LCA. The mechanism of CRX-associated LCA is not understood. Here, we identified a spontaneous mouse mutant with a frameshift mutation in Crx (CrxRip). We determined that CrxRip is a dominant mutation that results in congenital blindness with nonrecordable response by ERG and arrested photoreceptor differentiation with no associated degeneration. Expression of LCA-associated dominant CRX frameshift mutations in mouse retina mimicked the CrxRip phenotype, which was rescued by overexpression of WT CRX. Whole-transcriptome profiling using deep RNA sequencing revealed progressive and complete loss of rod differentiation factor NRL in CrxRip retinas. Expression of NRL partially restored rod development in CrxRip/+ mice. We show that the binding of homeobox transcription factor OTX2 at the Nrl promoter was obliterated in CrxRip mice and ectopic expression of OTX2 rescued the rod differentiation defect. Together, our data indicate that OTX2 maintains Nrl expression in developing rods to consolidate rod fate. Our studies provide insights into CRX mutation-associated congenital blindness and should assist in therapeutic design.
    The Journal of clinical investigation 01/2014; · 15.39 Impact Factor
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    ABSTRACT: Objective To determine whether genotypes at 2 major loci associated with late age-related macular degeneration (AMD), complement factor H (CFH) and age-related maculopathy susceptibility 2 (ARMS2), influence the relative benefits of Age-Related Eye Disease Study (AREDS) supplements. Design Unplanned retrospective evaluation of a prospective, randomized, placebo-controlled clinical trial of vitamins and minerals for the treatment of AMD. Subjects AREDS participants (mean age, 69 years) who were at risk of developing late AMD and who were randomized to the 4 arms of AREDS supplement treatment. Methods Analyses were performed using the Cox proportional hazards model to predict progression to late AMD (neovascular or central geographic atrophy). Statistical models, adjusted for age, gender, smoking status, and baseline AMD severity, were used to examine the influence of genotypes on the response to therapy with 4 randomly assigned arms of AREDS supplement components: placebo, antioxidants (vitamin C, vitamin E, β-carotene), zinc or a combination. Main Outcome Measures The influence of the genotype on the relative treatment response to the randomized components of the AREDS supplement, measured as progression to late AMD. Results Of the 1237 genotyped AREDS participants of white ethnicity, late AMD developed in 385 (31.1%) during the mean follow-up of 6.6 years. As previously demonstrated, CFH genotype (P = 0.005), ARMS2 (P< 0.0001), and supplement were associated individually with progression to late AMD. An interaction analysis found no evidence that the relative benefits of AREDS supplementation varied by genotype. Analysis of (1) CFH rs1061170 and rs1410996 combined with ARMS2 rs10490924 with the 4 randomly assigned arms of AREDS supplement and (2) analysis of the combination of CFH rs412852 and rs3766405 with ARMS2 c.372_815del443ins54 with the AREDS components resulted in no interaction (P = 0.06 and P = 0.45, respectively, before multiplicity adjustment). Conclusions The AREDS supplements reduced the rate of AMD progression across all genotype groups. Furthermore, the genotypes at the CFH and ARMS2 loci did not statistically significantly alter the benefits of AREDS supplements. Genetic testing remains a valuable research tool, but these analyses suggest it provides no benefits in managing nutritional supplementation for patients at risk of late AMD.
    Ophthalmology 01/2014; · 5.56 Impact Factor
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    ABSTRACT: Mutations in the CEP290 (cilia-centrosomal protein 290 kDa) gene in Leber congenital amaurosis (LCA) cause early onset visual loss but retained cone photoreceptors in the fovea, which is the potential therapeutic target. A cone-only mouse model carrying a Cep290 gene mutation, rd16;Nrl-/-, was engineered to mimic the human disease. In the current study, we determined the natural history of retinal structure and function in this murine model to permit design of pre-clinical proof-of-concept studies and allow progress to be made toward human therapy. Analyses of retinal structure and visual function in CEP290-LCA patients were also performed for comparison with the results in the model. Rd16;Nrl-/- mice were studied in the first 90 days of life with optical coherence tomography (OCT), electroretinography (ERG), retinal histopathology and immunocytochemistry. Structure and function data from a cohort of patients with CEP290-LCA (n = 15; ages 7-48) were compared with those of the model. CEP290-LCA patients retain a central island of photoreceptors with normal thickness at the fovea (despite severe visual loss); the extent of this island declined slowly with age. The rd16;Nrl-/- model also showed a relatively slow photoreceptor layer decline in thickness with ∼80% remaining at 3 months. The number of pseudorosettes also became reduced. By comparison to single mutant Nrl-/- mice, UV- and M-cone ERGs of rd16;Nrl-/- were at least 1 log unit reduced at 1 month of age and declined further over the 3 months of monitoring. Expression of GNAT2 and S-opsin also decreased with age. The natural history of early loss of photoreceptor function with retained cone cell nuclei is common to both CEP290-LCA patients and the rd16;Nrl-/- murine model. Pre-clinical proof-of-concept studies for uniocular therapies would seem most appropriate to begin with intervention at P35-40 and re-study after one month by assaying interocular difference in the UV-cone ERG.
    PLoS ONE 01/2014; 9(3):e92928. · 3.73 Impact Factor
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    ABSTRACT: The primary cilium originates from the mother centriole and participates in critical functions during organogenesis. Defects in cilia biogenesis or function lead to pleiotropic phenotypes. Mutations in centrosome-cilia gene CC2D2A result in Meckel and Joubert syndromes. Here we generate a Cc2d2a(-/-) mouse that recapitulates features of Meckel syndrome including embryonic lethality and multiorgan defects. Cilia are absent in Cc2d2a(-/-) embryonic node and other somatic tissues; disruption of cilia-dependent Shh signalling appears to underlie exencephaly in mutant embryos. The Cc2d2a(-/-) mouse embryonic fibroblasts (MEFs) lack cilia, although mother centrioles and pericentriolar proteins are detected. Odf2, associated with subdistal appendages, is absent and ninein is reduced in mutant MEFs. In Cc2d2a(-/-) MEFs, subdistal appendages are lacking or abnormal by transmission electron microscopy. Consistent with this, CC2D2A localizes to subdistal appendages by immuno-EM in wild-type cells. We conclude that CC2D2A is essential for the assembly of subdistal appendages, which anchor cytoplasmic microtubules and prime the mother centriole for axoneme biogenesis.
    Nature Communications 01/2014; 5:4207. · 10.02 Impact Factor
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    ABSTRACT: Age-related macular degeneration (AMD) is a leading cause of visual impairment worldwide. Aberrant DNA methylation within the promoter of IL17RC in peripheral blood mononuclear cells has recently been reported in AMD. To validate this association, we examined DNA methylation of the IL17RC promoter in peripheral blood. First, we used Illumina Human Methylation450 Bead Arrays, a widely accepted platform for measuring global DNA methylation. Second, methylation status at multiple sites within the IL17RC promoter was determined by bisulfite pyrosequencing in two cohorts. Third, a methylation-sensitive quantitative PCR-based assay was performed on a subset of samples. In contrast to previous findings, we did not find evidence of differential methylation between AMD cases and age-matched controls. We conclude that hypomethylation within the IL17RC gene promoter in peripheral blood is not suitable for use as a clinical biomarker of AMD. This study highlights the need for considerable replication of epigenetic association studies prior to clinical application.
    Cell Reports 12/2013; 5(6):1527-35. · 7.20 Impact Factor
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    ABSTRACT: Phototransduction machinery in vertebrate photoreceptors is contained within the membrane discs of outer segments. Daily renewal of 10% of photoreceptor outer segments requires stringent control of gene expression. Rhodopsin constitutes over 90% of the protein in rod discs, and its altered expression or transport is associated with photoreceptor dysfunction and/or death. Two cis-regulatory sequences have been identified upstream of the rhodopsin transcription start site. While the proximal promoter binds to specific transcription factors, including NRL and CRX, the rhodopsin enhancer region (RER) reportedly contributes to precise and high-level expression of rhodopsin in vivo. Here we report the identification of RER-bound proteins by mass spectrometry. We validate the binding of NonO (p54(nrb)), a protein implicated in coupling transcription to splicing, and three NonO-interacting proteins - hnRNP M, Ywhaz and Ppp1ca. NonO and its interactors can activate rhodopsin promoter in HEK293 cells and function synergistically with NRL and CRX. DNA binding domain of NonO is critical for rhodopsin promoter activation. Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) analysis demonstrates high occupancy of NonO at rhodopsin and a subset of phototransduction genes. Furthermore, shRNA knockdown of NonO in mouse retina leads to loss of rhodopsin expression and rod cell death, which can be partially rescued by a C-terminal NonO construct. RNA-seq analysis of the NonO shRNA treated retina revealed splicing defects and altered expression of genes, specifically those associated with phototransduction. Our studies identify an important contribution of NonO and its interacting modulator proteins in enhancing rod-specific gene expression and controlling rod homeostasis.
    Human Molecular Genetics 12/2013; · 7.69 Impact Factor
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    ABSTRACT: The present study examined the consequences of eliminating horizontal cells from the outer retina during embryogenesis upon the organization and assembly of the outer plexiform layer (OPL). Retinal horizontal cells exhibit a migration defect in Lim1-conditional knock-out (Lim1-CKO) mice and become mispositioned in the inner retina before birth, redirecting their dendrites into the inner plexiform layer. The resultant (mature) OPL, developing in the absence of horizontal cells, shows a retraction of rod spherules into the outer nuclear layer and a sprouting of rod bipolar cell dendrites to reach ectopic ribbon-protein puncta. Cone pedicles and the dendrites of type 7 cone bipolar cells retain their characteristic stratification and colocalization within the collapsed OPL, although both are atrophic and the spatial distribution of the pedicles is disrupted. Developmental analysis of Lim1-CKO retina reveals that components of the rod and cone pathways initially co-assemble within their normal strata in the OPL, indicating that horizontal cells are not required for the correct targeting of photoreceptor terminals or bipolar cell dendrites. As the rod spherules begin to retract during the second postnatal week, rod bipolar cells initially show no signs of ectopic growth, sprouting only subsequently and continuing to do so well after the eighth postnatal week. These results demonstrate the critical yet distinctive roles for horizontal cells on the rod and cone pathways and highlight a unique and as-yet-unrecognized maintenance function of an inhibitory interneuron that is not required for the initial targeting and co-stratification of other components in the circuit.
    Journal of Neuroscience 11/2013; 33(45):17847-62. · 6.91 Impact Factor
  • Rinki Ratnapriya, Anand Swaroop
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    ABSTRACT: Inherited retinal degenerative diseases (RDDs) display wide variation in their mode of inheritance, underlying genetic defects, age of onset, and phenotypic severity. Molecular mechanisms have not been delineated for many retinal diseases, and treatment options are limited. In most instances, genotype-phenotype correlations have not been elucidated because of extensive clinical and genetic heterogeneity. Next-generation sequencing (NGS) methods, including exome, genome, transcriptome and epigenome sequencing, provide novel avenues towards achieving comprehensive understanding of the genetic architecture of RDDs. Whole-exome sequencing (WES) has already revealed several new RDD genes, whereas RNA-Seq and ChIP-Seq analyses are expected to uncover novel aspects of gene regulation and biological networks that are involved in retinal development, aging and disease. In this review, we focus on the genetic characterization of retinal and macular degeneration using NGS technology and discuss the basic framework for further investigations. We also examine the challenges of NGS application in clinical diagnosis and management.
    Genome Medicine 10/2013; 5(9):84. · 4.94 Impact Factor
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    ABSTRACT: Macular degeneration is a common cause of blindness in the elderly. To identify rare coding variants associated with a large increase in risk of age-related macular degeneration (AMD), we sequenced 2,335 cases and 789 controls in 10 candidate loci (57 genes). To increase power, we augmented our control set with ancestry-matched exome-sequenced controls. An analysis of coding variation in 2,268 AMD cases and 2,268 ancestry-matched controls identified 2 large-effect rare variants: previously described p.Arg1210Cys encoded in the CFH gene (case frequency (fcase) = 0.51%; control frequency (fcontrol) = 0.02%; odds ratio (OR) = 23.11) and newly identified p.Lys155Gln encoded in the C3 gene (fcase = 1.06%; fcontrol = 0.39%; OR = 2.68). The variants suggest decreased inhibition of C3 by complement factor H, resulting in increased activation of the alternative complement pathway, as a key component of disease biology.
    Nature Genetics 09/2013; · 35.21 Impact Factor
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    ABSTRACT: Elevated intraocular pressure (IOP) is a major risk factor for glaucoma and is influenced by genetic and environmental factors. Recent genome-wide association studies (GWAS) reported associations with IOP at TMCO1 and GAS7, and with primary open-angle glaucoma (POAG) at CDKN2B-AS1, CAV1/CAV2, and SIX1/SIX6. To identify novel genetic variants and replicate the published findings, we performed GWAS and meta-analysis of IOP in >6,000 subjects of European ancestry collected in three datasets: the NEI Glaucoma Human genetics collaBORation, GLAUcoma Genes and ENvironment study, and a subset of the Age-related Macular Degeneration-Michigan, Mayo, AREDS and Pennsylvania study. While no signal achieved genome-wide significance in individual datasets, a meta-analysis identified significant associations with IOP at TMCO1 (rs7518099-G, p = 8.0 × 10(-8)). Focused analyses of five loci previously reported for IOP and/or POAG, i.e., TMCO1, CDKN2B-AS1, GAS7, CAV1/CAV2, and SIX1/SIX6, revealed associations with IOP that were largely consistent across our three datasets, and replicated the previously reported associations in both effect size and direction. These results confirm the involvement of common variants in multiple genomic regions in regulating IOP and/or glaucoma risk.
    Human Genetics 09/2013; · 4.63 Impact Factor
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    ABSTRACT: PURPOSE: Mutations in the RP2 gene are associated with 10-15% of X-linked Retinitis Pigmentosa (XLRP), a debilitating disorder characterized by the degeneration of retinal rod and cone photoreceptors. The molecular mechanism of pathogenesis of photoreceptor degeneration in XLRP-RP2 has not been elucidated, and no treatment is currently available. This study was undertaken to investigate the pathogenesis of RP2-associated retinal degeneration. METHODS: We introduced loxP sites that flank exon 2, a mutational hotspot in XLRP-RP2, in the mouse Rp2 gene. We then produced Rp2-null allele using transgenic mice that expressed Cre-recombinase under the control of ubiquitous CAG promoter. Electroretinography (ERG), histology, light microscopy, transmission electron microscopy (TEM), and immunofluorescence microscopy were performed to ascertain the effect of ablation of Rp2 on photoreceptor development, function, and protein trafficking. RESULTS: While no gross abnormalities were detected in the Rp2null mice, photopic (cone) and scotopic (rod) function as measured by ERG showed a gradual decline starting as early as 1 month of age. We also detected slow progressive degeneration of the photoreceptor membrane discs in the mutant retina. These defects were associated with mislocalization of cone opsins to the nuclear and synaptic layers and reduced rhodopsin content in the outer segment of mutant retina prior to the onset of photoreceptor degeneration. CONCLUSIONS: Our studies suggest that RP2 contributes to the maintenance of photoreceptor function and that cone opsin mislocalization represents an early step in XLRP caused by RP2 mutations. The Rp2null mice should serve as a useful preclinical model for testing gene- and cell-based therapies.
    Investigative ophthalmology & visual science 06/2013; · 3.43 Impact Factor
  • Anand Swaroop, Paul A Sieving
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    ABSTRACT: Nowhere in the field of medicine is the impact of genetics so evident as in diseases affecting vision and visual function. Vision is the most extensive of all human senses, and complex higher order tasks are largely dependent on the world we see. Loss of sight has devastating personal and social consequences, with tremendous burden on world resources. Investigations of healthy vision and visual disorders have been at the leading edge in genetics and biomedical research, creating major strides in diagnosis, therapy and clinical management. In this issue, eleven leading groups cover a broad spectrum of ocular diseases and discuss the genetic studies from the perspective of both clinicians and scientists.
    Clinical Genetics 05/2013; · 4.25 Impact Factor
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    ABSTRACT: IMPORTANCE For patients with X-linked retinitis pigmentosa and clinicians alike, phenotypic variability can be challenging because it complicates counseling regarding patients' likely visual prognosis. OBJECTIVE To evaluate the clinical findings from patients with X-linked retinitis pigmentosa with 13 distinct RPGR mutations and assess for phenotypic concordance or variability. DESIGN Retrospective medical record review of data collected from 1985 to 2011. SETTING Kellogg Eye Center, University of Michigan. PATIENTS A total of 42 patients with X-linked retinitis pigmentosa with mutations in RPGR. Age at first visit ranged from 4 to 53 years, with follow-up ranging from 1 to 11 visits (median follow-up time, 5.5 years; range, 1.4-32.7 years, for 23 patients with >1 visit). MAIN OUTCOMES AND MEASURES Clinical data assessed for concordance included visual acuity (VA), Goldmann visual fields (GVFs), and full-field electroretinography (ERG). Electroretinography phenotype (cone-rod vs rod-cone dysfunction) was defined by the extent of photopic vs scotopic abnormality. Qualitative GVF phenotype was determined by the GVF pattern, where central or peripheral loss suggested cone or rod dysfunction, respectively. Goldmann visual fields were also quantified and compared among patients. RESULTS Each mutation was detected in 2 or more related or unrelated patients. Five mutations in 11 patients displayed strong concordance of VA, while 4 mutations in 16 patients revealed moderate concordance of VA. A definitive cone-rod or rod-cone ERG pattern consistent among patients was found in 6 of 13 mutations (46.2%); the remaining mutations were characterized by patients demonstrating both phenotypes or who had limited data or nonrecordable ERG values. Concordant GVF phenotypes (7 rod-cone pattern vs 4 cone-rod pattern) were seen in 11 of 13 mutations (84.6%). All 6 mutations displaying a constant ERG pattern within the mutation group revealed a GVF phenotype consistent with the ERG findings. CONCLUSIONS AND RELEVANCE While VA and ERG phenotypes are concordant in only some patients carrying identical mutations, assessment of GVF phenotypes revealed stronger phenotypic conservation. Phenotypic concordance is important for establishing proper counseling of patients diagnosed as having X-linked retinitis pigmentosa, as well as for establishing accurate patient selection and efficacy monitoring in therapeutic trials.
    Jama Ophthalmology 05/2013; · 3.83 Impact Factor
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    ABSTRACT: Microglia, the resident immune cells of the central nervous system (CNS), are thought to contribute to the pathogenesis of age-related neurodegenerative disorders. It has been hypothesized that microglia undergo age-related changes in gene expression patterns that give rise to pathogenic phenotypes. We compared the gene expression profiles in microglia isolated ex vivo from the retinas of mice ranging from early adulthood to late senescence. We discovered that microglial gene expression demonstrated progressive change with increasing age, and involved genes that regulate microglial supportive functions and immune activation. Molecular pathways involving immune function and regulation, angiogenesis, and neurotrophin signaling demonstrated age-related change. In particular, expression levels of complement genes, C3 and CFB, previously associated with age-related macular degeneration (AMD), increased with aging, suggesting that senescent microglia may contribute to complement dysregulation during disease pathogenesis. Taken together, senescent microglia demonstrate age-related gene expression changes capable of altering their constitutive support functions and regulation of their activation status in ways relating to neuroinflammation and neurodegeneration in the CNS.
    Neurobiology of aging 04/2013; · 5.94 Impact Factor
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    ABSTRACT: Replacement of dysfunctional or dying photoreceptors offers a promising approach for retinal neurodegenerative diseases, including age-related macular degeneration and retinitis pigmentosa. Several studies have demonstrated the integration and differentiation of developing rod photoreceptors when transplanted in wild type or degenerating retina; however, the physiology and function of the donor cells are not adequately defined. Here, we describe the physiological properties of developing rod photoreceptors that are tagged with GFP driven by the promoter of rod differentiation factor, Nrl. GFP-tagged developing rods show Ca(2+) responses and rectifier outward currents that are smaller than those observed in fully developed photoreceptors, suggesting their immature developmental state. These immature rods also exhibit hyperpolarization-activated current (Ih ) induced by the activation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. When transplanted into the subretinal space of wild type or retinal degeneration mice, GFP-tagged developing rods can integrate into the photoreceptor outer nuclear layer in wild-type mouse retina, and exhibit Ca(2+) responses and membrane current comparable to native rod photoreceptors. A proportion of grafted rods develop rhodopsin-positive outer segment-like structures within two weeks after transplantation into the retina of Crx-knockout mice, and produce rectifier outward current and Ih upon membrane depolarization and hyperpolarization. GFP-positive rods derived from induced pluripotent stem (iPS) cells also display similar membrane current Ih as native developing rod photoreceptors, express rod-specific phototransduction genes, and HCN-1 channels. We conclude that Nrl-promoter driven GFP-tagged donor photoreceptors exhibit physiological characteristics of rods and that iPS cell-derived rods in vitro may provide a renewable source for cell replacement therapy.
    Stem Cells 03/2013; · 7.70 Impact Factor

Publication Stats

9k Citations
1,798.02 Total Impact Points

Institutions

  • 2009–2014
    • National Institutes of Health
      • Laboratory of Neurobiology-Neurodegeneration and Repair
      Maryland, United States
  • 2008–2014
    • National Eye Institute
      Maryland, United States
    • University of California, San Diego
      San Diego, California, United States
    • The University of Tennessee Health Science Center
      • Department of Ophthalmology
      Memphis, TN, United States
  • 2013
    • Universität Regensburg
      Ratisbon, Bavaria, Germany
  • 1991–2012
    • University of Michigan
      • • Department of Ophthalmology and Visual Sciences
      • • Center for Statistical Genetics
      • • Department of Human Genetics
      Ann Arbor, MI, United States
    • Stanford Medicine
      Stanford, California, United States
    • University of Texas Health Science Center at San Antonio
      San Antonio, Texas, United States
  • 2011
    • Institute of Genetics and Molecular Medicine
      Edinburgh, Scotland, United Kingdom
    • NEI Corporation
      Somerset, New Jersey, United States
    • University of Massachusetts Medical School
      • Department of Ophthalmology
      Worcester, Massachusetts, United States
  • 1997–2011
    • University of Pennsylvania
      • • Department of Ophthalmology
      • • Department of Medicine
      Philadelphia, PA, United States
  • 2004–2009
    • Johns Hopkins University
      • McKusick-Nathans Institute of Genetic Medicine
      Baltimore, Maryland, United States
    • École Supérieure d'Electricité
      Gif, Île-de-France, France
    • National Research Council
      Roma, Latium, Italy
  • 2007
    • Champalimaud Neuroscience Program
      Lisboa, Lisbon, Portugal
    • National Brain Research Centre
      • Division of Cellular and Molecular Neuroscience
      Gurgaon, Haryana, India
  • 2003–2004
    • Western General Hospital
      Edinburgh, Scotland, United Kingdom
  • 1997–2004
    • Lund University
      • Department of Ophthalmology
      Lund, Skane, Sweden
  • 1998–1999
    • University of Illinois at Chicago
      • Department of Ophthalmology and Visual Sciences (Chicago)
      Chicago, IL, United States
  • 1996
    • Howard Hughes Medical Institute
      Maryland, United States
    • Concordia University–Ann Arbor
      Ann Arbor, Michigan, United States
    • Samuel Lunenfeld Research Institute
      Toronto, Ontario, Canada
  • 1985–1993
    • Yale University
      • • Department of Genetics
      • • Department of Molecular Biophysics and Biochemistry
      New Haven, CT, United States
  • 1988–1990
    • Yale-New Haven Hospital
      New Haven, Connecticut, United States