A NOVEL MISSENSE MUTATION IN THE RDS/PERIPHERIN GENE ASSOCIATED WITH RETINAL PATTERN DYSTROPHY Omar R. Ahmad, MD, Radha Ayyagari, PhD, David N. Zacks, MD, PhD
Purpose: To present a case of retinal pattern dystrophy and the genetic analysis identifying the molecular basis of the disease. Methods: A 46-year-old man with a 6-year history of vision loss of the right eye. A clinical exam revealed pattern dystrophy of the retina bilaterally, with more involvement of the right eye. Results: Molecular diagnostic analysis of the retinal degeneration slow (RDS)/peripherin gene showed a novel change at nucleotide position 665 (G665C) that alters the amino acid at position 222 from cysteine to serine (C222S). Conclusion: This study describes an RDS/peripherin mutation in a case of retinal pattern dystrophy, which is the first identification of this mutation to our knowledge. RETINAL CASES & BRIEF REPORTS 4:84 – 85, 2010
From the Department of Ophthalmology and Visual Sciences, The Kellogg Eye Center, University of Michigan Medical School, Ann Arbor, Michigan.
gle family can result in a number of different retinal phenotypes.4 We describe a novel mutation of the RDS/ peripherin gene in a man with retinal pattern dystrophy.
P
attern dystrophy is a group of dominantly inherited photoreceptor dystrophies that often cause mild-to-moderate central vision disturbances in midlife. A variety of yellow, orange, or gray pigment deposition patterns can be seen in the macula at the level of the retina pigment epithelium. Gass1 subdivided pattern dystrophy according to the distribution of pigment in the macula: adult-onset foveomacular vitelliform type, butterfly-shaped type, reticular type, multifocal pattern dystrophy simulating fundus flavimaculatus, and fundus pulverulentus with contiguous changes. Pattern dystrophy is both phenotypically and genetically heterogeneous. Mutations in the retinal degeneration slow (RDS)/peripherin gene are a not infrequent cause of pattern dystrophy as well as other retinal diseases such as retinitis pigmentosa, retinitis punctata albescens, and cone-rod degeneration.2–9 In fact, the same RDS/peripherin mutation within a sin-
Case Report A 46-year-old white man presented with 6 years of decreased vision in the right eye. He noted that the vision loss was fairly sudden and that it affected primarily his central vision. He had no significant medical history but did report a family history of macular degeneration in his mother. On examination, visual acuity was 20/60 in the right eye and 20/20 in the left eye. Amsler grid testing showed a discrete area of central blurring on the right. Dilated examination showed yellow deposits in the central macula of both eyes, with greater involvement of the right eye (Figure 1). A clinical diagnosis of pattern dystrophy was made, and the patient agreed to have molecular diagnostic testing. Mutation analysis was carried out following guidelines of Clinical Laboratory Improvement Amendments.10 The coding sequences of the RDS/peripherin gene (all three exons) were amplified by a polymerase chain reaction from genomic DNA. The resulting DNA fragments were directly sequenced using the same polymerase chain reaction primers. Molecular diagnostic analysis of the RDS/peripherin gene showed a heterozygous sequence change at nucleotide position 665 (G665C) that alters the amino acid at position 222 from cysteine to serine (C222S). This change was not been previously reported. The patient had 4 other changes in the heterozygous state RDS/peripherin gene (V106V, E304E, K310R, G338D) that have been previously reported as noncausative polymorphisms. The test confirmed a molecular diagnosis of pattern dystrophy due to a novel mutation in the RDS/peripherin gene.
The authors have no proprietary interests or conflicts of interest. Reprint requests: Dr. David Zacks, MD, PhD, University of Michigan Kellogg Eye Center, 1000 Wall Street, Ann Arbor, MI 48105; e-mail: [email protected]
84
85
A MUTATION IN RETINAL PATTERN DYSTROPHY
References 1. 2.
3.
4. Fig. 1. Fundus photographs showing yellow deposits in the central macula of both eyes, with greater involvement of the right eye.
Discussion The RDS/peripherin gene is found on chromosome 6p and encodes a photoreceptor-specific membrane glycoprotein that is likely involved in the stabilization of outer segment disk membranes.11 It forms an oligomeric complex that has a large intradiscal loop of ⬃150 amino acids joining the third and fourth transmembrane segments. There are 7 highly conserved cysteine residues within these loops at amino acid positions 150, 165, 166, 213, 214, 222, and 250. Using an in vitro analysis system allowing for site-directed mutagenesis, Goldberg et al12 found that replacement of any of the seven conserved cysteine significantly altered the folding and subunit assembly properties of the final protein product. They suggested that the C150 residue was involved in intermolecular disulfide bonding, whereas the other six conserved cysteine residues are crucial for proper folding and subunit assembly secondary to intramolecular disulfide bonding. Mutations at four of the seven conserved cysteine residues have been found to cause retinal disease in humans. A Cys-Tyr substitution at position 165 or CysSer substitution at 214 causes retinitis pigmentosa and Cys-Arg substitution at 213 or Cys-Tyr substitution at 214 produces a pattern dystrophy phenotype.13–16 Although we do not have DNA information on any relatives of our patients, the known examples of cysteine residue mutations in conjunction with the biochemical analysis of Goldberg et al12 demonstrate that a single mutation in any one cysteine residue can be causative for pattern dystrophy. As such, we submit this case report as the first description of the C222S RDS/peripherin mutation as a cause for the retinal pattern dystrophy observed in our patient. Key words: macular dystrophy, pattern dystrophy, retinal degeneration slow/peripherin.
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Gass JD. Stereoscopic Atlas of Macular Diseases: Diagnosis and Treatment. Vol. 1. St. Louis, MO: C.V. Mosby; 1997:314–325. Wells J, Wroblewski J, Keen J, et al. Mutations in the human retinal degeneration slow (RDS) gene can cause either retinitis pigmentosa or macular dystrophy. Nat Genet 1993;3: 213–218. Farrar GJ, Kenna P, Jordan SA, et al. A three-base-pair deletion in the peripherin-RDS gene in one form of retinitis pigmentosa. Nature 1991;354:478 – 480. Apfelstedt-Sylla E, Theischen M, Ruther K, Wedemann H, Gal A, Zrenner E. Extensive intrafamilial and interfamilial phenotypic variation among patients with autosomal dominant retinal dystrophy and mutations in the human RDS/ peripherin gene. Br J Ophthalmol 1995;79:28 –34. Felbor U, Schilling H, Weber BH. Adult vitelliform macular dystrophy is frequently associated with mutations in the peripherin/RPS gene. Hum Mutat 1997;10:301–309. Fossarello M, Bertini C, Galantuomo MS, et al. Deletion in the peripherin/RDS gene in two unrelated Sardinian families with autosomal dominant butterfly-shaped macular dystrophy. Arch Ophthalmol 1996;114:448 – 456. Francis PJ, Schultz DW, Gregory AM, et al. Genetic and phenotypic heterogeneity in pattern dystrophy. Br J Ophthalmol 2005;89:1115–1119. Grover S, Fishman GA, Stone EM. Atypical presentation of pattern dystrophy in two families with peripherin/RDS mutations. Ophthalmology 2002;109:1110 –1117. Kajiwara K, Sandberg MA, Berson EL, et al. A null mutation in the human peripherin/RPS gene in a family with autosomal dominant retinitis punctata albescens. Nat Genet 1993;3:208–212. Downs K, Zacks DN, Caruso R, et al. Molecular testing for hereditary retinal disease as part of clinical care. Arch Ophthalmol 2007;125:252–258. Osborne NN, Chader GJ. Progress in Retinal and Eye Research. Tarrytown, NY: Pergamon; 1994:271–299. Goldberg AF, Loewen CJ, Molday RS. Cysteine residues of photoreceptor peripherin/RDS: role in subunit assembly and autosomal dominant retinitis pigmentosa. Biochemistry 1998; 37:680 – 685. Souied EH, Rozet JM, Gerber S, et al. Two novel missense mutations in the peripherin/RDS gene in two unrelated French patients with autosomal dominant retinitis pigmentosa. Eur J Ophthalmol 1998;8:98 –101. Payne AM, Dowes SM, Bessant DA, Bird AC, Battacharya SS. Founder effect, seen in the British population, of the 172 peripherin/RDS mutation-and further refinement of genetic positioning of the peripherin/RDS gene. Am J Hum Genet 1998;62:192–195. Farrar GJ, Kenna P. Autosomal dominant retinitis pigmentosa: a novel mutation at the peripherin/RDS locus in the original 6p-linked pedigree. Genomics 1992;14:805– 807. Trujillo MJ, Martinez-Gimeno M, Gime´nez A, et al. Two novel mutations (Y141H; C214Y) and previously published mutation (R142W) in the RDS-peripherin gene in autosomal dominant macular dystrophies in Spanish families. Hum Mutat 2001;17:80.
Purpose: To present a case of retinal pattern dystrophy and the genetic analysis identifying the molecular basis of the disease. Methods: A 46-year-old man with a 6-year history of vision loss of the right eye. A clinical exam revealed pattern dystrophy of the retina bilaterally, with more involvement of the right eye. Results: Molecular diagnostic analysis of the retinal degeneration slow (RDS)/peripherin gene showed a novel change at nucleotide position 665 (G665C) that alters the amino acid at position 222 from cysteine to serine (C222S). Conclusion: This study describes an RDS/peripherin mutation in a case of retinal pattern dystrophy, which is the first identification of this mutation to our knowledge. RETINAL CASES & BRIEF REPORTS 4:84 – 85, 2010
From the Department of Ophthalmology and Visual Sciences, The Kellogg Eye Center, University of Michigan Medical School, Ann Arbor, Michigan.
gle family can result in a number of different retinal phenotypes.4 We describe a novel mutation of the RDS/ peripherin gene in a man with retinal pattern dystrophy.
P
attern dystrophy is a group of dominantly inherited photoreceptor dystrophies that often cause mild-to-moderate central vision disturbances in midlife. A variety of yellow, orange, or gray pigment deposition patterns can be seen in the macula at the level of the retina pigment epithelium. Gass1 subdivided pattern dystrophy according to the distribution of pigment in the macula: adult-onset foveomacular vitelliform type, butterfly-shaped type, reticular type, multifocal pattern dystrophy simulating fundus flavimaculatus, and fundus pulverulentus with contiguous changes. Pattern dystrophy is both phenotypically and genetically heterogeneous. Mutations in the retinal degeneration slow (RDS)/peripherin gene are a not infrequent cause of pattern dystrophy as well as other retinal diseases such as retinitis pigmentosa, retinitis punctata albescens, and cone-rod degeneration.2–9 In fact, the same RDS/peripherin mutation within a sin-
Case Report A 46-year-old white man presented with 6 years of decreased vision in the right eye. He noted that the vision loss was fairly sudden and that it affected primarily his central vision. He had no significant medical history but did report a family history of macular degeneration in his mother. On examination, visual acuity was 20/60 in the right eye and 20/20 in the left eye. Amsler grid testing showed a discrete area of central blurring on the right. Dilated examination showed yellow deposits in the central macula of both eyes, with greater involvement of the right eye (Figure 1). A clinical diagnosis of pattern dystrophy was made, and the patient agreed to have molecular diagnostic testing. Mutation analysis was carried out following guidelines of Clinical Laboratory Improvement Amendments.10 The coding sequences of the RDS/peripherin gene (all three exons) were amplified by a polymerase chain reaction from genomic DNA. The resulting DNA fragments were directly sequenced using the same polymerase chain reaction primers. Molecular diagnostic analysis of the RDS/peripherin gene showed a heterozygous sequence change at nucleotide position 665 (G665C) that alters the amino acid at position 222 from cysteine to serine (C222S). This change was not been previously reported. The patient had 4 other changes in the heterozygous state RDS/peripherin gene (V106V, E304E, K310R, G338D) that have been previously reported as noncausative polymorphisms. The test confirmed a molecular diagnosis of pattern dystrophy due to a novel mutation in the RDS/peripherin gene.
The authors have no proprietary interests or conflicts of interest. Reprint requests: Dr. David Zacks, MD, PhD, University of Michigan Kellogg Eye Center, 1000 Wall Street, Ann Arbor, MI 48105; e-mail: [email protected]
84
85
A MUTATION IN RETINAL PATTERN DYSTROPHY
References 1. 2.
3.
4. Fig. 1. Fundus photographs showing yellow deposits in the central macula of both eyes, with greater involvement of the right eye.
Discussion The RDS/peripherin gene is found on chromosome 6p and encodes a photoreceptor-specific membrane glycoprotein that is likely involved in the stabilization of outer segment disk membranes.11 It forms an oligomeric complex that has a large intradiscal loop of ⬃150 amino acids joining the third and fourth transmembrane segments. There are 7 highly conserved cysteine residues within these loops at amino acid positions 150, 165, 166, 213, 214, 222, and 250. Using an in vitro analysis system allowing for site-directed mutagenesis, Goldberg et al12 found that replacement of any of the seven conserved cysteine significantly altered the folding and subunit assembly properties of the final protein product. They suggested that the C150 residue was involved in intermolecular disulfide bonding, whereas the other six conserved cysteine residues are crucial for proper folding and subunit assembly secondary to intramolecular disulfide bonding. Mutations at four of the seven conserved cysteine residues have been found to cause retinal disease in humans. A Cys-Tyr substitution at position 165 or CysSer substitution at 214 causes retinitis pigmentosa and Cys-Arg substitution at 213 or Cys-Tyr substitution at 214 produces a pattern dystrophy phenotype.13–16 Although we do not have DNA information on any relatives of our patients, the known examples of cysteine residue mutations in conjunction with the biochemical analysis of Goldberg et al12 demonstrate that a single mutation in any one cysteine residue can be causative for pattern dystrophy. As such, we submit this case report as the first description of the C222S RDS/peripherin mutation as a cause for the retinal pattern dystrophy observed in our patient. Key words: macular dystrophy, pattern dystrophy, retinal degeneration slow/peripherin.
5.
6.
7.
8.
9.
10.
11. 12.
13.
14.
15.
16.
Gass JD. Stereoscopic Atlas of Macular Diseases: Diagnosis and Treatment. Vol. 1. St. Louis, MO: C.V. Mosby; 1997:314–325. Wells J, Wroblewski J, Keen J, et al. Mutations in the human retinal degeneration slow (RDS) gene can cause either retinitis pigmentosa or macular dystrophy. Nat Genet 1993;3: 213–218. Farrar GJ, Kenna P, Jordan SA, et al. A three-base-pair deletion in the peripherin-RDS gene in one form of retinitis pigmentosa. Nature 1991;354:478 – 480. Apfelstedt-Sylla E, Theischen M, Ruther K, Wedemann H, Gal A, Zrenner E. Extensive intrafamilial and interfamilial phenotypic variation among patients with autosomal dominant retinal dystrophy and mutations in the human RDS/ peripherin gene. Br J Ophthalmol 1995;79:28 –34. Felbor U, Schilling H, Weber BH. Adult vitelliform macular dystrophy is frequently associated with mutations in the peripherin/RPS gene. Hum Mutat 1997;10:301–309. Fossarello M, Bertini C, Galantuomo MS, et al. Deletion in the peripherin/RDS gene in two unrelated Sardinian families with autosomal dominant butterfly-shaped macular dystrophy. Arch Ophthalmol 1996;114:448 – 456. Francis PJ, Schultz DW, Gregory AM, et al. Genetic and phenotypic heterogeneity in pattern dystrophy. Br J Ophthalmol 2005;89:1115–1119. Grover S, Fishman GA, Stone EM. Atypical presentation of pattern dystrophy in two families with peripherin/RDS mutations. Ophthalmology 2002;109:1110 –1117. Kajiwara K, Sandberg MA, Berson EL, et al. A null mutation in the human peripherin/RPS gene in a family with autosomal dominant retinitis punctata albescens. Nat Genet 1993;3:208–212. Downs K, Zacks DN, Caruso R, et al. Molecular testing for hereditary retinal disease as part of clinical care. Arch Ophthalmol 2007;125:252–258. Osborne NN, Chader GJ. Progress in Retinal and Eye Research. Tarrytown, NY: Pergamon; 1994:271–299. Goldberg AF, Loewen CJ, Molday RS. Cysteine residues of photoreceptor peripherin/RDS: role in subunit assembly and autosomal dominant retinitis pigmentosa. Biochemistry 1998; 37:680 – 685. Souied EH, Rozet JM, Gerber S, et al. Two novel missense mutations in the peripherin/RDS gene in two unrelated French patients with autosomal dominant retinitis pigmentosa. Eur J Ophthalmol 1998;8:98 –101. Payne AM, Dowes SM, Bessant DA, Bird AC, Battacharya SS. Founder effect, seen in the British population, of the 172 peripherin/RDS mutation-and further refinement of genetic positioning of the peripherin/RDS gene. Am J Hum Genet 1998;62:192–195. Farrar GJ, Kenna P. Autosomal dominant retinitis pigmentosa: a novel mutation at the peripherin/RDS locus in the original 6p-linked pedigree. Genomics 1992;14:805– 807. Trujillo MJ, Martinez-Gimeno M, Gime´nez A, et al. Two novel mutations (Y141H; C214Y) and previously published mutation (R142W) in the RDS-peripherin gene in autosomal dominant macular dystrophies in Spanish families. Hum Mutat 2001;17:80.
