[Studies on retinitis pigmentosa. 19. Synthesis of retinal-amine complex].
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PURPOSE: We identified genetic mutations and characterized their associated phenotypes in patients with retinitis pigmentosa. METHODS: Patients with retinitis pigmentosa were prospectively examined and screened for genetic mutations. RESULTS: A 46-year-old man with retinitis pigmentosa was found to have a heterozygous mutation in the peripherin/RDS gene (arginine-46-stop). He had late onset of symptoms and demarcated peripheral retinal atrophy. All five first-degree relatives including his parents had no detectable mutations or retinitis pigmentosa. Genotypic data were consistent with reported family structure. CONCLUSIONS: This study shows that new dominant mutations are a rare cause of isolated, or simplex, cases of retinitis pigmentosa. Identification of these mutations is helpful for genetic counseling.
Evoked otoacoustic emissions (EOE) offer a unique opportunity to measure objectively the function of outer hair cells in human beings. In this paper the Authors report a study carried out employing EOE evaluation on cochlear function in subjects with retinitis pigmentosa. Nine patients with retinitis pigmentosa with normal hearing in both ears upon traditional audiometric evaluation were studied. The frequency spectrum of the EOE was taken into consideration, evaluated in frequency bands of 50 Hz, in order to ascertain the presence or absence of the emissions and, when present, their amplitude. These data were compared statistically, using the Student's T Test, to those obtained in a homogeneous control group of normal subjects. In subjects with retinitis pigmentosa, average EOE intensity values were statistically lower than those found in normal subjects. In fact, the Student's T Test evaluation revealed significant differences in EOE intensity in 64 of the 127 frequency bands examined. Moreover, the distribution of the EOE in patients with retinitis pigmentosa proved to be more discontinuous than that observed in the normal subjects. These data appear to indicate authentic alterations in the cochlear mechanics in patients with retinitis pigmentosa. Such alterations may well be related to outer hair cell lesions. It seems likely that the auditory system is involved in retinitis pigmentosa degenerative processes more frequently than traditional audiometric tests have been able to show.
In this paper the authors compare a group of patients suffering from isolated form of retinitis pigmentosa with these with Usher syndrome.
Retinitis pigmentosa (RP) is a group of inherited progressive retinal diseases affecting about 1 in 3500 people worldwide. So far, there is no prevention or cure, with permanent visual loss or even blindness the ultimate consequence usually after midlife. The genetics of RP are complex. It can be sporadic, autosomal dominant, autosomal recessive, or X-linked. Thirty-two genes are known to be associated with RP, sometimes the same gene gets involved in different inheritance traits. Some RP cases have a digenic cause. About 60% RP cases still have no known genetic cause. A large number of mutations cause RP, and they can be deletions, insertions, or substitutions that cause missense mutations or truncations. The RHO, RP1, and RPGR genes contribute the greatest number of known mutations causative of RP. But there is no single mutation that alone accounts for more than 10% of unrelated patients. Genetic testing for RP therefore requires screening for a group of genes. High-throughput and automated sequence detection technologies are essential. Due to the complexity in phenotype and genetics, and the fact that RP is untreatable, genetic testing for presymptomatic diagnosis of RP is controversial. Meanwhile, new genes are still to be identified, mostly by family linkage and sib-pair analysis. Research on gene therapy for RP requires information on gene mutations causative of RP.
Unilateral retinitis pigmentosa (URP) is a rare tapetoretinal dystrophy affecting only one eye. The François and Verriest criteria are necessary to make a correct diagnosis of URP: exclude all infective etiologies, check that the clinical signs of retinitis are present in the affected eye and ensure the total absence of any signs or symptoms of retinitis pigmentosa in the fellow eye. The standard electroretinogram and standard electro-oculogram are very useful for the correct diagnosis. Other pigmentary retinopathies simulating retinitis pigmentosa have to be excluded, such as previous retinal inflammatory diseases like syphilis, rubeola, other viral diseases and onchocerciasis. In this paper, 4 cases of URP are reported.
Electroretinograms (ERGs) have provided criteria for establishing the diagnosis of retinitis pigmentosa in early life even at a time when fundus abnormalities visible with the ophthalmoscope are minimal or absent. Patients with widespread progressive forms of retinitis pigmentosa have shown not only reduced amplitudes but also delays in cone or rod b-wave implicit times, or both, while patients with self-limited sector retinitis pigmentosa or stationary forms of night blindness have had reduced amplitudes with normal b-wave implicit times. In families with retinitis pigmentosa ERGs can be used not only to identify which patients are affected but also to establish which patients are normal as those patients, age 6 and over, with normal cone and rod amplitudes and normal cone and rod b-wave implicit times have not been observed to develop primary retinitis pigmentosa at a later time. ERGs from patients with retinitis pigmentosa and allied night blinding disorders are presented to show their usefulness in genetic typing, documenting natural; histories, and defining possible pathogenetic mechanisms. The potential application of the ERG in evaluating the efficacy of therapeutic trials is also considered.
Globular excrescences of the optic nerve associated with retinitis pigmentosa have been interpreted as drusen or as astrocytic hamartomas. The histopathologic and ultrastructural findings of globular excrescences of the peripapillary region of the optic nerve associated with retinitis pigmentosa were described in a 22-year-old patient who died in a car accident. From our findings we conclude that the globular excrescences of the optic nerve associated with retinitis pigmentosa are definitely drusen and not astrocytic hamartomas.
PURPOSE: To determine the frequency and characteristics of optic disc and parapapillary nerve fiber layer drusen in patients with retinitis pigmentosa and to attempt to document any differences in the frequency within different genetic subtypes of retinitis pigmentosa. METHODS: This retrospective case series reviewed 117 patients with autosomal-dominant, 84 with autosomal-recessive, and 61 with X-linked recessive forms of retinitis pigmentosa. Color fundus photographs were reviewed independently by three investigators. The presence of optic disc or parapapillary nerve fiber layer drusen was documented only when all three observers concurred as to their presence. The number (isolated or multiple), site (disc, parapapillary, or both), and bilaterality (unilateral or bilateral) were noted in each patient. RESULTS: Optic disc or parapapillary nerve fiber layer drusen or both were observed in 11 patients (9.4%) with autosomal-dominant, 6 patients (7.1%) with autosomal-recessive, and 7 patients (11.5%) with X-linked recessive types of retinitis pigmentosa. The differences in the observed frequencies were not statistically significant (P = 0.67). Overall, the frequency of optic nerve head or parapapillary drusen or both in 262 patients with retinitis pigmentosa was 9.2%. CONCLUSION: In a large population of patients with retinitis pigmentosa, our findings suggest that approximately 10% are likely to show optic nerve fiber layer drusen involving the optic disc or parapapillary regions or both. The frequency does not vary significantly between different genetic subtypes.
PURPOSE: To investigate the diagnostic potential of multifocal electroretinography for the evaluation of retinal affection by retinitis pigmentosa in a clinical setting. METHODS: For this prospective study, multifocal electroretinograms were obtained from 38 patients who matched the inclusion criteria of either a detectable photopic Ganzfeld response or visual fields of 10 degrees or more, and from 30 normal volunteers. Recordings were performed with the visual evoked response imaging system, using a resolution of 61 hexagonal elements within a 30-degree visual field. The results of the left eye of each patient and control subject were used for statistical evaluation by the Mann-Whitney U test. RESULTS: The 38 eligible patients included those with Usher syndrome types I and II (one patient and six patients, respectively) and those with autosomal-recessive (18), X-recessive (two), and autosomal-dominant (11) forms of retinitis pigmentosa. In 27 (71%) of these 38 patients, at least a central response of the multifocal electroretinogram was detectable. Loss of multifocal electroretinogram response density in patients with retinitis pigmentosa was significant (P < .00001) in all five eccentricity groups (concentric rings), with a progression from center to periphery. Implicit time was significantly elevated in the third eccentricity group (P < .0038) and increased further toward the periphery (P < .00001). The results did not differ notably between retinitis pigmentosa subgroups. CONCLUSIONS: Because the multifocal electroretinogram differentiates between affected and nonaffected retinal areas, eccentricity-dependent changes in both amplitude and implicit time were found. It can therefore add to the diagnostic information of many patients with retinitis pigmentosa.
OBJECTIVES: To identify suspected RDS mutations in families in which different people have been identified with either generalised retinal dystrophy or macular dystrophy. METHODS: Two families with a retinal dystrophy were extensively phenotyped and blood was taken for mutation analysis of the RDS (all) and ROM1 (retinitis pigmentosa patients only) genes. RESULTS: A novel p.Trp94X mutation in RDS was found in all three affected members of a two-generation family that was associated with retinitis pigmentosa in the son, pattern dystrophy in the daughter and fundus flavimaculatus in the mother. In the second family, the proband with retinitis pigmentosa carried a p.Arg220Trp mutation. The mother, who was unavailable for mutation screening, had adult vitelliform macular dystrophy. No ROM1 mutations were found in those with retinitis pigmentosa in either family. CONCLUSION: Mutations in RDS can be associated with an intrafamilial variation in retinal disease. The phenotypes range from Stargardt-like macular dystrophy to classic retinitis pigmentosa. CLINICAL RELEVANCE: Intrafamilial phenotypic variation may be due to the presence of environmental or genetic modifying factors. The presence of a modifying-sequence change in the coding region of ROM1 for two people with retinitis pigmentosa from two families with intrafamilial variation in RDS mutation phenotype has been excluded in this study.
The conditions of three siblings with concurrent retinitis pigmentosa and von Hippel tumors were evaluated. Their eyes showed the characteristic arteriolar attenuation expected in retinitis pigmentosa, except in the retinal sectors containing von Hippel tumors, where large feeder vessels supplied each tumor. Two of the siblings suffered further loss of vision as a result of large exudative retinal detachments associated with the von Hippel tumors. Both patients had satisfactory resolution of the retinal detachments following cryotherapy and laser therapy of their retinal tumors. The third sibling has a small retinal detachment that should te amenable to therapy. Visually handicapped patients require routine follow-up examinations to detect new diseases that may result in low of the remaining vision.
PURPOSE: To compare the prevalence of thyroid disease in patients with retinitis pigmentosa, in patients with gyrate atrophy of the choroid and retina, and in patients with no history of ocular disease. METHOD: Forty-four patients with retinitis pigmentosa, 34 patients with gyrate atrophy, and 30 normal control patients with no ocular disease were evaluated in a case-control study for the presence of thyroid disease. RESULTS: Thyroid disease was diagnosed in six of 44 patients with retinitis pigmentosa and seven of 34 patients with gyrate atrophy but in only one of 30 control patients. Compared with control patients, the odds ratio for the occurrence of thyroid disease was 6.2 for patients with retinitis pigmentosa and 12.7 for patients with gyrate atrophy. CONCLUSION: These data suggest an increased occurrence of thyroid disease in patients with retinitis pigmentosa and gyrate atrophy.
Two members of a family with autosomal dominant retinitis pigmentosa were found to have a cytosine-to-thymine mutation in the second nucleotide of codon 267 in the rhodopsin gene that resulted in a proline-to-leucine change. Two members of another family with autosomal dominant retinitis pigmentosa showed a guanine-to-thymine mutation in the first nucleotide of codon 190 in the rhodopsin gene that resulted in an aspartate-to-tyrosine change. Three members from a third family with autosomal dominant retinitis pigmentosa were also found to have a mutation in codon 190; however, this guanine-to-adenine mutation in the first nucleotide of codon 190 resulted in an aspartate-to-asparagine change. The relatively less severe functional retinal impairment in our patients with a transmembrane codon 267 rhodopsin gene mutation is generally comparable with that observed in a previously described codon 58 transmembrane mutation. The two families with different intradiscal codon 190 mutations showed a considerable difference in severity of their disease.
Eight members of a family with autosomal dominant retinitis pigmentosa were found to have a cytosine-to-guanine (C-to-G) transversion mutation in the second nucleotide of codon 58 of the rhodopsin gene, causing a substitution of the amino acid arginine for threonine. Five of these individuals were examined clinically. There was a distinct phenotypic expression of the gene defect within this family that included a regional predilection for pigmentary changes in the inferior and inferonasal parts of the retina, as well as field impairment predominantly in the superior hemisphere. Characteristic electroretinographic recordings and psychophysical threshold profiles also helped to identify this phenotype that, on a relative basis, causes less severe photoreceptor cell functional impairment than often occurs in other subtypes of retinitis pigmentosa. This report documents the association of a clinically recognizable phenotype in a family with autosomal dominant retinitis pigmentosa and a specific gene defect at the molecular level.
X-linked progressive retinal atrophy (XLPRA) in the Siberian husky dog is a naturally occurring X-linked retinopathy closely resembling X-linked retinitis pigmentosa (XLRP) in humans. In affected males, initial degeneration of rods is followed by cone degeneration and complete retinal atrophy; carrier females have random patches of rod degeneration consistent with random X chromosome inactivation. By typing the XLPRA pedigree with five intragenic markers [dystrophin, retinitis pigmentosa GTPase regulator ( RPGR ), tissue inhibitor of metalloproteinases 1, androgen receptor and factor IX], we established a linkage map of the canine X chromosome, and confirmed that the order of these five genes is identical to that on the human X. XLPRA was tightly linked to an intragenic RPGR polymorphism (LOD 11.7, zero recombination), thus confirming locus homology with RP3. We cloned the full-length canine RPGR cDNA and three additional splice variants. No disease-causing mutation was found in the RPGR-coding sequence of the four splice variants characterized, a finding similar to approximately 80% of human XLRP patients whose disease maps to the RP3 locus. In addition, there were no significant differences in the proportional expression of each splice variant in normal and pre-degenerate XLPRA-affected retina. Expression of all RPGR splice variants increased later in the disease, when retinas were undergoing active degeneration. The results provide further evidence of cross-species retention of a complex splicing pattern in the 3' portion of RPGR, the functional significance of which is unknown. In addition, the possibility of another disease locus in the RP3 region is supported.
Sixty-eight consecutive patients with retinitis pigmentosa were studied to determine the frequency of the nonpigmented form of the disease. There was an overall incidence of 22%. Fifty percent of all cases had no characteristic pigmentation, if the duration of night vision difficulty was three years or less. The nonpigmented form of retinitis pigmentosa was frequently an early stage of the disease and not an unusual or atypical variant. Patients without the pigmentary changes characteristic of the disorder also showed less functional impairment: the electroretinographic b wave was more apt to be recordable, although impaired, and the rod threshold, as determined by dark adaptation measurement, was less elevated. The clinician should suspect retinitis pigmentosa, even in the absence of pigmentary changes, if there is a family history of the disorder, night blindness, peripheral field loss, and an impaired or nonrecordable electroretinographic response.
PURPOSE: To examine the sites of cone sensitivity loss in patients with retinitis pigmentosa by comparing focal electroretinographic and psychophysical modulation thresholds. METHODS: Both psychophysical and electrophysiologic increment threshold curves were obtained in retinitis pigmentosa patients and a group of age-matched, normally-sighted adults. RESULTS: The majority of the retinitis pigmentosa data could be accounted for by a vertical displacement of the normal curve. The retinitis pigmentosa patients showed similar patterns of cone sensitivity losses using both techniques. CONCLUSIONS: The combined electrophysiologic and psychophysical results provide support for an outer retina locus for these cone sensitivity losses. The data suggest that these deficits may be caused by a spatially independent loss of cone photoreceptors with normal adaptation properties in the remaining photoreceptors.