Molecular Analysis and Genetic Mapping of the Rhodopsin Gene in Families with Autosomal Dominant Retinitis Pigmentosa

doi:10.1006/geno.1993.1309

Genomics

Volume 17, Issue 1, July 1993, Pages 230-233

https://doi.org/10.1006/geno.1993.1309 Get rights and content

Abstract

Eighty-eight patients/families with autosomal dominant retinitis pigmentosa (RP) were screened for rhodopsin mutations. Direct sequencing revealed 13 different mutations in a total of 14 (i.e., 16%) unrelated patients. Five of these mutations (T4K, Q28H, R135G, F220C, and C222R) have not been reported so far. In addition, multipoint linkage analysis was performed on two large families with autosomal dominant RP due to rhodopsin mutations by using five DNA probes from 3q21-q24. No tight linkage was found between the rhodopsin locus (RHO) and D3S47 (θ_max = 0.08). By six-point analysis, RHO was localized in the region between D3S21 and D3S47, with a maximum lod score of 13.447 directly at D3S20.

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Cited by (65)

Mutations in rhodopsin, endothelin B receptor, and CC chemokine receptor 5 in large animals: Modeling human diseases
2022, Progress in Molecular Biology and Translational Science
Citation Excerpt :
Naturally occurring T4R RHO was identified from English Mastiff dogs with a naturally occurring dominant retinal degeneration26 (Table 1). Mutation at the same position in human opsin (T4K) also causes retinitis pigmentosa.51 English Mastiff dogs with RHO mutation with a slowly progressive retinal degeneration share similar features as human autosomal dominant retinitis pigmentosa caused by Class B RHO mutations (refers to a milder phenotype, with retained rod function at least in certain retinal regions).52
G protein-coupled receptors (GPCRs) are the largest family of cell membrane receptors involved in modulating almost all physiological processes by transducing extracellular signals into the cytoplasm. Dysfunctions of GPCR-regulated signaling result in diverse human diseases, making GPCRs the most popular drug targets for human medicine. Large animals share higher similarities (in physiology and metabolism) with humans than rodents. Similar to findings in human genetics, diverse diseases caused by mutations in GPCR genes have also been discovered in large animals. Rhodopsin, endothelin B receptor, and CC chemokine receptor type 5 have been shown to be involved in human retinitis pigmentosa, Hirschsprung disease, and HIV infection/AIDS, respectively, and several mutations of these GPCRs have also been identified from large animals. The large animals with naturally occurring mutations of these GPCRs provide an opportunity to gain a better understanding of the pathogenesis of human diseases, and can be used for preclinical trials of therapies for human diseases. In this review, we aim to summarize the naturally occurring mutations of these three GPCRs in large animals and humans.
Spectrum-frequency and genotype–phenotype analysis of rhodopsin variants
2021, Experimental Eye Research
Citation Excerpt :
The 52 variants were classified into the categories of missense (45), splicing site (three), inframe (two), nonsense (one), and frameshift (one) changes. The phenotype analysis, segregation analysis, bioinformatics analysis, and previous evidence suggested that 17 of the 52 variants were potentially pathogenic (Table 1) (Dryja et al., 1991; Inglehearn et al., 1992; Sung et al., 1991; Xu et al., 2014; Zhou et al., 2018; Keen et al., 1991; Macke et al., 1993; Haim et al., 1996; Inglehearn et al., 1991; Souied et al., 1994; Li et al., 2010; Bunge et al., 1993; Dryja et al., 1990a). These include 15 missens, one inframe deletion and one nonsense variant for 33 families with RP.
Mutations in RHO are the most common cause of autosomal dominant retinitis pigmentosa. However, the pathogenicity of many RHO variants is questionable. This study was designed to investigate the genotype–phenotype correlation for RHO variants. These RHO variants were collected from the in-house exome sequencing data of 7092 probands suffering from different types of eye conditions. The variants were classified using bioinformatics tools, family segregation, and clinical phenotypes. The RHO variants were assessed using multiple online tools and a genotype–phenotype analysis based on the data collected from of ours, gnomAD, and published literature. Totally, 52 heterozygous variants of RHO were detected in the 7092 probands. Of these 52, 17 were potentially pathogenic, were present in 35 families, and comprised 15 missense variants, one inframe deletion and one nonsense variant. All the 15 missense variants were predicted to be damaging by five different online tools. The analysis of the clinical data of the patients from the 35 families revealed certain common features, of an early damage to both the rods and the cones, relatively preserved visual acuity in adulthood, and mid-peripheral tapetoretinal degeneration with pigmentation or RPE atrophy. Our data, the data from gnomAD, and the systematic review of the 246 previously reported variants suggest that approximately two-thirds of the rare missense variants and most of the truncated variants involving upstream of K296 are likely benign. This study provides a brief summary of the characteristics of the pathogenic RHO variants. It emphasizes that the systematic evaluation of these variants at the individual-gene level is crucial in the current era of clinical genetic testing even for a well-known gene such as RHO.
Identification of two novel RHO mutations in Chinese retinitis pigmentosa patients
2019, Experimental Eye Research
Citation Excerpt :
It caused CAG to TAG and brought in a stop codon at amino acid position 28 (p. Q28X). The Q28H missense mutation at the same position was previously reported to cause adRP (Bunge et al., 1993). However, the nonsense mutation c.82C > T here was homozygous and responsible for the proband in family E.
Retinitis pigmentosa (RP) is a group of genetically heterogeneous retinal diseases with more than 80 identified causative genes to date. Mutations in the RHO (rhodopsin, OMIM, 180380) are the most common cause of autosomal dominant RP (adRP) worldwide. RHO is also one of the few RP genes that can cause autosomal recessive RP (arRP). To explore the frequency of RP mutations in Chinese populations, panel-based NGS (next-generation sequencing) screening and Sanger sequencing validation were performed for RP patients from 72 unrelated Chinese families. Here we reported the identified mutations only in the RHO gene. Our results showed that 4 mutations in RHO were detected in 5 (6.94%) of the 72 RP families, including two known missense mutations, c.158C > G (p.P53R) and c.551A > C (p.Q184P), and two novel mutations, c.34delC (p.P12NA) and c.82C > T (p.Q28X). The c.34delC (p.P12NA) mutation was detected in heterozygous state in one patient with intermediate RP phenotype. The c.82C > T (p.Q28X) mutation was found in a homozygous state in one proband with advanced RP phenotype at the age of 32. Clinical examination of the heterozygous carriers of c.82C > T (p.Q28X) in that family showed that the father at the age of 60s experienced no symptoms of RP and normal fundus examinations but displayed reduced electroretinography (ERG) and abnormal visual field. The sister and brother at the age of 30s showed no typical aspects of RP phenotypes. Our results not only expand the mutation spectrum of the RHO gene, but also suggest that the 2 null mutations might play minor dominant effects, leading to less severe and slower retinal degeneration in heterozygous state and more severe phenotype in homozygous state.
Analysis of conserved glutamate and aspartate residues in drosophila rhodopsin 1 and their influence on spectral tuning
2015, Journal of Biological Chemistry
Citation Excerpt :
These findings are consistent with the idea that Glu-181 plays an important role in the early stages of rhodopsin activation and that a negative charge at this position stabilizes the protonated Schiff base in later photoactivated intermediates. Consistent with the importance of Glu-181 in rhodopsin function is the observation that human mutations in rhodopsin at this site (E181K) are associated with autosomal dominant retinitis pigmentosa and have been identified repeatedly in diverse populations (68–70). When expressed in vitro the E181K mutant pigment is unable to bind chromophore (66).
The molecular mechanisms that regulate invertebrate visual pigment absorption are poorly understood. Studies of amphioxus G_o-opsin have demonstrated that Glu-181 functions as the counterion in this pigment. This finding has led to the proposal that Glu-181 may function as the counterion in other invertebrate visual pigments as well. Here we describe a series of mutagenesis experiments to test this hypothesis and to also test whether other conserved acidic amino acids in Drosophila Rhodopsin 1 (Rh1) may serve as the counterion of this visual pigment. Of the 5 Glu and Asp residues replaced by Gln or Asn in our experiments, none of the mutant pigments shift the absorption of Rh1 by more than 6 nm. In combination with prior studies, these results suggest that the counterion in Drosophila Rh1 may not be located at Glu-181 as in amphioxus, or at Glu-113 as in bovine rhodopsin. Conversely, the extremely low steady state levels of the E194Q mutant pigment (bovine opsin site Glu-181), and the rhabdomere degeneration observed in flies expressing this mutant demonstrate that a negatively charged residueat this position is essential for normal rhodopsin function in vivo. This work also raises the possibility that another residue or physiologic anion may compensate for the missing counterion in the E194Q mutant.
Genetic high throughput screening in Retinitis Pigmentosa based on high resolution melting (HRM) analysis
2013, Experimental Eye Research
Retinitis Pigmentosa (RP) involves a group of genetically determined retinal diseases caused by a large number of mutations that result in rod photoreceptor cell death followed by gradual death of cone cells. Most cases of RP are monogenic, with more than 80 associated genes identified so far. The high number of genes and variants involved in RP, among other factors, is making the molecular characterization of RP a real challenge for many patients. Although HRM has been used for the analysis of isolated variants or single RP genes, as far as we are concerned, this is the first study that uses HRM analysis for a high-throughput screening of several RP genes. Our main goal was to test the suitability of HRM analysis as a genetic screening technique in RP, and to compare its performance with two of the most widely used NGS platforms, Illumina and PGM-Ion Torrent technologies. RP patients (n = 96) were clinically diagnosed at the Ophthalmology Department of Donostia University Hospital, Spain. We analyzed a total of 16 RP genes that meet the following inclusion criteria: 1) size: genes with transcripts of less than 4 kb; 2) number of exons: genes with up to 22 exons; and 3) prevalence: genes reported to account for, at least, 0.4% of total RP cases worldwide. For comparison purposes, RHO gene was also sequenced with Illumina (GAII; Illumina), Ion semiconductor technologies (PGM; Life Technologies) and Sanger sequencing (ABI 3130xl platform; Applied Biosystems). Detected variants were confirmed in all cases by Sanger sequencing and tested for co-segregation in the family of affected probands. We identified a total of 65 genetic variants, 15 of which (23%) were novel, in 49 out of 96 patients. Among them, 14 (4 novel) are probable disease-causing genetic variants in 7 RP genes, affecting 15 patients. Our HRM analysis-based study, proved to be a cost-effective and rapid method that provides an accurate identification of genetic RP variants. This approach is effective for medium sized (<4 kb transcript) RP genes, which constitute over 80% of the total of known RP genes.
Retinitis pigmentosa
2006, Lancet
Hereditary degenerations of the human retina are genetically heterogeneous, with well over 100 genes implicated so far. This Seminar focuses on the subset of diseases called retinitis pigmentosa, in which patients typically lose night vision in adolescence, side vision in young adulthood, and central vision in later life because of progressive loss of rod and cone photoreceptor cells. Measures of retinal function, such as the electroretinogram, show that photoreceptor function is diminished generally many years before symptomic night blindness, visual-field scotomas, or decreased visual acuity arise. More than 45 genes for retinitis pigmentosa have been identified. These genes account for only about 60% of all patients; the remainder have defects in as yet unidentified genes. Findings of controlled trials indicate that nutritional interventions, including vitamin A palmitate and omega-3-rich fish, slow progression of disease in many patients. Imminent treatments for retinitis pigmentosa are greatly anticipated, especially for genetically defined subsets of patients, because of newly identified genes, growing knowledge of affected biochemical pathways, and development of animal models.

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Short CommunicationMolecular Analysis and Genetic Mapping of the Rhodopsin Gene in Families with Autosomal Dominant Retinitis Pigmentosa

Abstract

Short Communication
Molecular Analysis and Genetic Mapping of the Rhodopsin Gene in Families with Autosomal Dominant Retinitis Pigmentosa