WDR19 : An ancient, retrograde, intraflagellar ciliary protein is mutated in autosomal recessive retinitis pigmentosa and in Senior‐Loken syndrome

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99013/1/cge12196.pd

Ocular and extra-ocular features of patients with Leber congenital amaurosis and mutations in CEP290

Contains fulltext : 108895.pdf (publisher's version ) (Open Access)PURPOSE: This study investigated the centrosomal protein, 290-KD (CEP290) associated genotype and ocular and extra-ocular phenotype in 18 patients with Leber congenital amaurosis (LCA). METHODS: Eighteen patients with LCA from 14 families with mutations in the CEP290 gene were identified with sequencing or with heteroduplex analysis. Ophthalmic examinations were performed on all patients. Scans of the central nervous system were reassessed in three patients and obtained in two. Renal function was evaluated in all patients. Ultrasonography of the kidneys was performed in six patients. RESULTS: Eight patients (from five families) carried the c.2991+1655A>G mutation homozygously. Nine solitary patients carried this variant combined with a nonsense, frameshift, or splice site mutation on the second allele. One new nonsense mutation was identified: c.1078C>T. Fourteen patients (from 12 families) had been completely blind from birth or had light perception. The best-recorded visual acuity was 20/200. Peripheral fundus changes appeared to be progressive with a relatively preserved posterior pole. Novel ophthalmic features for the CEP290 phenotype were Coats-like exudative vasculopathy in two patients, a small chorioretinal coloboma in one patient, and well defined, small, atrophic spots at the level of the retinal pigment epithelium causing a dot-like appearance in five patients. Some CEP290 patients exhibited systemic abnormalities. We found abnormal proprioception in two patients and mild mental retardation in one. One patient was infertile due to immobile spermatozoa. No renal abnormalities were detected. CONCLUSIONS: CEP290-associated LCA has a severe, progressive, and clinically identifiable phenotype. Distinct extra-ocular findings were noted, which may be attributed to ciliary dysfunction

Mutations in PNPLA6 are linked to photoreceptor degeneration and various forms of childhood blindness

Blindness due to retinal degeneration affects millions of people worldwide, but many disease-causing mutations remain unknown. PNPLA6 encodes the patatin-like phospholipase domain containing protein 6, also known as neuropathy target esterase (NTE), which is the target of toxic organophosphates that induce human paralysis due to severe axonopathy of large neurons. Mutations in PNPLA6 also cause human spastic paraplegia characterized by motor neuron degeneration. Here we identify PNPLA6 mutations in childhood blindness in seven families with retinal degeneration, including Leber congenital amaurosis and Oliver McFarlane syndrome. PNPLA6 localizes mostly at the inner segment plasma membrane in photo-receptors and mutations in Drosophila PNPLA6 lead to photoreceptor cell death. We also report that lysophosphatidylcholine and lysophosphatidic acid levels are elevated in mutant Drosophila. These findings show a role for PNPLA6 in photoreceptor survival and identify phospholipid metabolism as a potential therapeutic target for some forms of blindness.Foundation Fighting Blindness CanadaCanadian Institutes of Health ResearchNIHCharles University institutional programmesBIOCEV-Biotechnology and Biomedicine Centre of the Academy of Sciences and Charles University, from the European Regional Development FundMinistry of Health of the Czech RepublicGraduate School of Life Sciences (University of Wuerzburg)Government of Canada through Genome CanadaOntario Genomics InstituteGenome QuebecGenome British ColumbiaMcLaughlin CentreCharles Univ Prague, Inst Inherited Metab Disorders, Fac Med 1, Prague 12000 2, Czech RepublicMcGill Univ, Dept Human Genet, Fac Med, Montreal, PQ H3A 0G1, CanadaGenome Quebec Innovat Ctr, Montreal, PQ H3A 0G1, CanadaClin Res Inst Montreal, Cellular Neurobiol Res Unit, Montreal, PQ H2W 1R7, CanadaMcGill Univ, Montreal, PQ H3A 0G4, CanadaMcGill Univ, Ctr Hlth, Montreal Childrens Hosp, McGill Ocular Genet Lab, Montreal, PQ H3H 1P3, CanadaMcGill Univ, Ctr Hlth, Montreal Childrens Hosp, Dept Paediat Surg, Montreal, PQ H3H 1P3, CanadaMcGill Univ, Ctr Hlth, Montreal Childrens Hosp, Dept Human Genet, Montreal, PQ H3H 1P3, CanadaMcGill Univ, Ctr Hlth, Montreal Childrens Hosp, Dept Ophthalmol, Montreal, PQ H3H 1P3, CanadaUniv Alberta, Royal Alexandra Hosp, Dept Ophthalmol & Visual Sci, Edmonton, AB T5H 3V9, CanadaCharles Univ Prague, Inst Biol & Med Genet, Fac Med 1, Prague 12000 2, Czech RepublicBaylor Coll Med, Dept Mol & Human Genet, Human Genome Sequencing Ctr, Houston, TX 77030 USAUniversidade Federal de São Paulo, Dept Neurol, Div Gen Neurol, BR-04021001 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Neurol, Ataxia Unit, BR-04021001 São Paulo, BrazilNewcastle Univ, Inst Med Genet, Newcastle Upon Tyne NE1 3BZ, Tyne & Wear, EnglandUniversidade Federal de São Paulo, Dept Ophthalmol, BR-04021001 São Paulo, BrazilSo Gen Hosp, Dept Clin Genet, Glasgow G51 4TF, Lanark, ScotlandCardiff Univ, Sch Med, Inst Med Genet, Cardiff CF14 4XN, S Glam, WalesHadassah Hebrew Univ Med Ctr, Dept Ophthalmol, IL-91120 Jerusalem, IsraelOregon Hlth & Sci Univ, Oregon Inst Occupat Hlth Sci, Portland, OR 97239 USAUniv Wurzburg, Lehrstuhl Neurobiol & Genet, D-97074 Wurzburg, GermanyUniv Montreal, Dept Med, Montreal, PQ H3T 1P1, CanadaMcGill Univ, Dept Anat & Cell Biol, Div Expt Med, Montreal, PQ H3A 2B2, CanadaUniversidade Federal de São Paulo, Dept Neurol, Div Gen Neurol, BR-04021001 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Neurol, Ataxia Unit, BR-04021001 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Ophthalmol, BR-04021001 São Paulo, BrazilNIH: EY022356-01NIH: EY018571-05NIH: NS047663-09Charles University institutional programmes: PRVOUK-P24/LF1/3Charles University institutional programmes: UNCE 204011Charles University institutional programmes: SVV2013/266504BIOCEV-Biotechnology and Biomedicine Centre of the Academy of Sciences and Charles University, from the European Regional Development Fund: CZ.1.05/1.1.00/02.0109Ministry of Health of the Czech Republic: NT13116-4/2012Ministry of Health of the Czech Republic: NT14015-3/2013Ontario Genomics Institute: OGI-049Web of Scienc

A common allele in RPGRIP1L is a modifier of retinal degeneration in ciliopathies

Despite rapid advances in the identification of genes involved in disease, the predictive power of the genotype remains limited, in part owing to poorly understood effects of second-site modifiers. Here we demonstrate that a polymorphic coding variant of RPGRIP1L (retinitis pigmentosa GTPase regulator-interacting protein-1 like), a ciliary gene mutated in Meckel-Gruber (MKS) and Joubert (JBTS) syndromes, is associated with the development of retinal degeneration in individuals with ciliopathies caused by mutations in other genes. As part of our resequencing efforts of the ciliary proteome, we identified several putative loss-of-function RPGRIP1L mutations, including one common variant, A229T. Multiple genetic lines of evidence showed this allele to be associated with photoreceptor loss in ciliopathies. Moreover, we show that RPGRIP1L interacts biochemically with RPGR, loss of which causes retinal degeneration, and that the Thr229-encoded protein significantly compromises this interaction. Our data represent an example of modification of a discrete phenotype of syndromic disease and highlight the importance of a multifaceted approach for the discovery of modifier alleles of intermediate frequency and effect.This work was supported by grants R01EY007961 from the National Eye Institute (H.K. and A.S.), R01HD04260 from the National Institute of Child Health and Development (N.K.), R01DK072301, R01DK075972 (N.K.), R01DK068306, R01DK064614, R01DK069274 (F.H.), NRSA fellowship F32 DK079541 (E.E.D.) from the National Institute of Diabetes, Digestive and Kidney disorders, Intramural program of NEI (A.S.), the Macular Vision Research Foundation (N.K.), the Foundation for Fighting Blindness (H.K., S.S.B., A.S. and N.K.), the Foundation for Fighting Blindness Canada (R.K.K.), Le Fonds de la recherche en sante du Québec (FRSQ) (R.K.K.), Research to Prevent Blindness (A.S.), Harold Falls Collegiate Professorship (A.S.), the Midwest Eye Banks and Transplantation Center (H.K.), the Searle Scholars Program (M.A.B.), the Deutsche Forschungsgemeinschaft (DFG grant BE 3910/4-1; C.B.) the UK Medical Research Council (grant number G0700073; C.A.J.), NIHR Biomedical Research Centre for Ophthalmology (S.S.B.) and EU-GENORET Grant LSHG-CT-2005-512036 (S.S.B.). F.H. is an investigator of the Howard Hughes Medical Institute (HHMI) and a Doris Duke Distinguished Clinical Scientist (DDCF)

NAD-biosynthetic enzyme NMNAT1 reduces early behavioral impairment in the htau mouse model of tauopathy

NAD metabolism and the NAD biosynthetic enzymes nicotinamide nucleotide adenylyltransferases (NMNATs) are thought to play a key neuroprotective role in tauopathies, including Alzheimer’s disease. Here, we investigated whether modulating the expression of the NMNAT nuclear isoform NMNAT1, which is important for neuronal maintenance, influences the development of behavioral and neuropathological abnormalities in htau mice, which express non-mutant human tau isoforms and represent a model of tauopathy relevant to Alzheimer’s disease. Prior to the development of cognitive symptoms, htau mice exhibit tau hyperphosphorylation associated with a selective deficit in food burrowing, a behavior reminiscent to activities of daily living which are impaired early in Alzheimer’s disease. We crossed htau mice with Nmnat1 transgenic and knockout mice and tested the resulting offspring until the age of 6 months. We show that overexpression of NMNAT1 ameliorates the early deficit in food burrowing characteristic of htau mice. At 6 months of age, htau mice did not show neurodegenerative changes in both the cortex and hippocampus, and these were not induced by downregulating NMNAT1 levels. Modulating NMNAT1 levels produced a corresponding effect on NMNAT enzymatic activity but did not alter NAD levels in htau mice. Although changes in local NAD levels and subsequent modulation of NAD-dependent enzymes cannot be ruled out, this suggests that the effects seen on behavior may be due to changes in tau phosphorylation. Our results suggest that increasing NMNAT1 levels can slow the progression of symptoms and neuropathological features of tauopathy, but the underlying mechanisms remain to be established

Rescue of Photoreceptor Degeneration by Curcumin in Transgenic Rats with P23H Rhodopsin Mutation

The P23H mutation in the rhodopsin gene causes rhodopsin misfolding, altered trafficking and formation of insoluble aggregates leading to photoreceptor degeneration and autosomal dominant retinitis pigmentosa (RP). There are no effective therapies to treat this condition. Compounds that enhance dissociation of protein aggregates may be of value in developing new treatments for such diseases. Anti-protein aggregating activity of curcumin has been reported earlier. In this study we present that treatment of COS-7 cells expressing mutant rhodopsin with curcumin results in dissociation of mutant protein aggregates and decreases endoplasmic reticulum stress. Furthermore we demonstrate that administration of curcumin to P23H-rhodopsin transgenic rats improves retinal morphology, physiology, gene expression and localization of rhodopsin. Our findings indicate that supplementation of curcumin improves retinal structure and function in P23H-rhodopsin transgenic rats. This data also suggest that curcumin may serve as a potential therapeutic agent in treating RP due to the P23H rhodopsin mutation and perhaps other degenerative diseases caused by protein trafficking defects

Genetic Basis of Inherited Macular Dystrophies and Implications for Stem Cell Therapy

Untreatable hereditary macular dystrophy (HMD) presents a major burden to society in terms of the resulting patient disability and the cost to the healthcare provision system. HMD results in central vision loss in humans sufficiently severe for blind registration, and key issues in the development of therapeutic strategies to target these conditions are greater understanding of the causes of photoreceptor loss and the development of restorative procedures. More effective and precise analytical techniques coupled to the development of transgenic models of disease have led to a prolific growth in the identification and our understanding of the genetic mutations that underly HMD. Recent successes in driving differentiation of pluripotent cells towards specific somatic lineages have led to the development of more efficient protocols that can yield enriched populations of a desired phenotype. Retinal pigmented epithelial cells and photoreceptors derived from these are some of the most promising cells that may soon be used in the treatment of specific HMD, especially since rapid developments in the field of induced pluripotency have now set the stage for the production of patient-derived stem cells that overcome the ethical and methodological issues surrounding the use of embryonic derivatives. In this review we highlight a selection of HMD which appear suitable candidates for combinatorial restorative therapy, focusing specifically on where those photoreceptor loss occurs. This technology, along with increased genetic screening, opens up an entirely new pathway to restore vision in patients affected by HMD

Cost-effective sequence analysis of 113 genes in 1,192 probands with retinitis pigmentosa and Leber congenital amaurosis

Introduction: Retinitis pigmentosa (RP) and Leber congenital amaurosis (LCA) are two groups of inherited retinal diseases (IRDs) where the rod photoreceptors degenerate followed by the cone photoreceptors of the retina. A genetic diagnosis for IRDs is challenging since >280 genes are associated with these conditions. While whole exome sequencing (WES) is commonly used by diagnostic facilities, the costs and required infrastructure prevent its global applicability. Previous studies have shown the cost-effectiveness of sequence analysis using single molecule Molecular Inversion Probes (smMIPs) in a cohort of patients diagnosed with Stargardt disease and other maculopathies. Methods: Here, we introduce a smMIPs panel that targets the exons and splice sites of all currently known genes associated with RP and LCA, the entire RPE65 gene, known causative deep-intronic variants leading to pseudo-exons, and part of the RP17 region associated with autosomal dominant RP, by using a total of 16,812 smMIPs. The RP-LCA smMIPs panel was used to screen 1,192 probands from an international cohort of predominantly RP and LCA cases. Results and discussion: After genetic analysis, a diagnostic yield of 56% was obtained which is on par with results from WES analysis. The effectiveness and the reduced costs compared to WES renders the RP-LCA smMIPs panel a competitive approach to provide IRD patients with a genetic diagnosis, especially in countries with restricted access to genetic testing