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  • 1
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Cyclic nucleotide-gated (CNG) ion channels serve as final targets of signal transduction in vertebrate photoreceptors. While the basic mechanisms of phototransduction are similar in rod and cone photoreceptors, both cell types express distinct sets of components of the transduction pathway. We report here the cloning of the cDNA encoding the α-subunit of the cGMP-gated channel of human cone photoreceptors. The open reading frame predicts a polypeptide of 694 amino acid residues with conserved functional parts and amino acid positions typical for the α-subunit of CNG-channels. Heterologous expression of the cDNA in Xenopus oocytes gave rise to cGMP-gated channel activity. Antiserum directed against the C-terminus of the bovine cone CNG channel α-subunit crossreacted specifically with the heterologously expressed polypeptide and stained cone photoreceptors and weakly also the outer plexiform layer in human retinal sections. Northern blot analysis detected a prominent mRNA species of ∼3.8 kb in human retina. The entire gene spans ∼30 kb of genomic sequence and is located on the pericentric band q11.2 of human chromosome 2. The gene is composed of seven exons, with introns located at positions which are preserved with respect to the human rod gene, indicating a common ancestral gene structure. RT-PCR analysis gave no evidence for alternatively spliced transcripts.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1433-0423
    Keywords: Key words Leber hereditary optic neuropathy • LHON • Mitochondrial DNA • mtDNA • Peripapillary microangiopathy • Point mutation ; Schlüsselwörter Lebersche Optikusneuropathie • LHON • mitochondriale DNA • mtDNA • peripapilläre Mikroangiopathie • Punktmutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Fragestellung: Die klinische Verdachtsdiagnose Lebersche Optikusneuropathie (LHON) kann durch molekulargenetische Untersuchungen gesichert werden. LHON wird assoziiert mit dem Auftreten von Punktmutationen in der mitochondrialen DNA (mtDNA), als sicher gilt die pathogenetische Bedeutung eines Basenaustausches an den Positionen 3460, 11 778 und 14 484 der Nukleotidabfolge. Patienten und Methoden: Wir untersuchten 29 Patienten, die in den letzten 3 Jahren (1995–1997) mit der klinischen Verdachtsdiagnose Lebersche Optikusneuropathie überwiesen wurden. Ergebnisse: In 9 Fällen konnte die primäre Verdachtsdiagnose LHON klinisch und molekulargenetisch bestätigt werden, während sich 20 Patienten molekulargenetisch negativ für LHON zeigten und in 7 Fällen eine degenerative Netzhaut- oder Aderhauterkrankung, in 6 Fällen einen vaskulären Optikusprozeß aufwiesen. 3 Patienten hatten eine Tabak-Alkohol-Amblyopie, 2 eine beidseitige Neuritis nervi optici und 2 eine dominant erbliche Optikusatrophie. Schlußfolgerung: Die klinische Verdachtsdiagnose Lebersche Optikusneuropathie stützt sich auf einen meist beidseitigen Visusverlust, den Nachweis eines Zentral- oder Zentrozaekalskotoms im Gesichtsfeld und auf ein Pseudoödem der Papille, das nach Wochen in eine Optikusatrophie übergeht. Pathognomonisch für LHON ist die peripapilläre Mikroangiopathie, die aber während des Krankheitsverlaufs verschwindet. Eine positive Familienanamnese (weitere Erkrankte in der maternalen Linie) erhärtet den Verdacht zusätzlich. Die Fehleranalyse der klinischen Diagnostik zeigte, daß die Beachtung zusätzlicher makularer Veränderungen, die korrekte Interpretation der Gesichtsfeldbefunde, die Berücksichtigung des für LHON typischen klinischen Befundes einer peripapillären Mikroangiopathie und der Nachweis eines maternalen Erbgangs anhand einer Stammbaumanalyse dazu beitragen, eine Fehldiagnose LHON zu vermeiden.
    Notes: Background: Leber's hereditary optic neuropathy is associated with point mutations in the mitochondrial DNA (mtDNA) that appear to be pathogenic for this disease. These mutations affect nucleotide positions 3460, 11 778 and 14 484. Materials and methods: We reviewed the clinical and molecular genetic characteristics of 29 visually symptomatic patients with the clinical diagnosis of LHON. Results: Nine patients really suffered from LHON, but in 20 patients other ocular diseases could be proven. Degeneration of the retina and choroid was most common (seven patients), followed by vascular optic disease (six patients). Three patients suffered from tobacco-alcohol amblyopia, two from optic neuritis and two from autosomal dominant optic neuropathy. Conclusions: The clinical diagnosis of LHON is strengthened by a proven maternal inheritance and clinical signs such as a severe decrease in visual acuity, central or centrocecal scotomas in the perimetry and pseudoedema of the optic disc, followed by optic atrophy. Pathognomonic clinical signs of LHON are twisted vessels and ectatic capillaries in the fundus of these patients and their relatives of the maternal line, i. e., peripapillary microangiopathy. A careful analysis of the patients' pedigrees, anamnesis and the functional and morphological results of the clinical examinations helps to avoid misdiagnosis of the disease. However, the expensive and time-consuming molecular genetic analysis is always necessary to confirm or exclude the diagnosis of LHON.
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  • 3
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Total colourblindness (OMIM 216900), also referred to as rod monochromacy (RM) or complete achromatopsia, is a rare, autosomal recessive inherited and congenital disorder characterized by photophobia, reduced visual acuity, nystagmus and the complete inability to discriminate between colours. ...
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 246 (1995), S. 739-744 
    ISSN: 1617-4623
    Keywords: Group II intron ; Plant mitochondria ; Regulation of splicing ; RNA editing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The trans-splicing group II intron c/d in the Oenothera mitochondrial nad1 gene is modified by RNA editing in domain 6. This C-to-U conversion generates the typical domain 6 structure, which prompted us to speculate that this RNA editing event might be essential for splicing. To test this hypothesis, we investigated the influence of unedited and edited sequences of the Oenothera intron on splicing in vitro. The stem of domain 6 of intron nad1-c/d was transplanted into the autocatalytic yeast intron aI5c, yielding chimeras with the genomic C and the edited U, respectively, 5′ of the branchpoint A. When incubated under self-splicing conditions, only the edited chimera was released as a lariat, while the precursor with the genomically coded C remained inactive. Our results support the hypothesis that Oenothera group II intron nadl-c/d cannot be spliced from the primary transcript without previous editing in domain 6.
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  • 5
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  · Background: Leber’s hereditary optic neuropathy (LHON) mostly affects young males. In patients carrying one of the primary mutations the risk to develop LHON is 50% for males and 10% for females. We report a family with predominantly young girls affected. · Methods: In a family with 14 known maternal relatives (11 females, 3 males) 9 patients in 4 generations developed LHON. Eight of the 9 patients were females. Three affected females could be examined and followed. · Results: The only affected male showed the typical course of LHON with acute visual loss in both eyes (20/400–20/800) within 6 weeks at 20 years of age. Eight of 9 females developed signs of LHON. In these females acute visual loss occurred at about 10 years of age. Final visual acuity was about 20/200. Central or paracentral scotomata, color vision defects and delayed P100 latencies in the VEP were seen. Ophthalmoscopy showed hyperemic discs in the acute stage and optic atrophy in later stages. Molecular genetic analysis revealed the presence of the mtDNA ND4/np11778 mutation in this family. Specific clinical or additional molecular genetic risk factors could not be detected. · Conclusion: Families with LHON may show considerable variations of the clinical course and the gender- or age-specific risk. We present a family with a high disease penetrance of 64% and a 2 times higher risk for young females than for males. Furthermore, early visual loss in this family is permanent.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Graefe's archive for clinical and experimental ophthalmology 237 (1999), S. 745-752 
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract · Background: Leber’s hereditary optic neuropathy (LHON) is a maternally inherited ocular disease associated with mutations in the mitochondrial DNA (mtDNA). We describe the clinical and molecular genetic findings in a LHON patient and his family with a new mtDNA mutation at np14568 in the ND6 gene. · Methods: Ophthalmological examination was performed in one affected male and two maternal relatives. Direct sequence analysis of the complete mtDNA protein coding region was initiated in the affected patient. Four unaffected maternal relatives also underwent molecular genetic evaluation. · Results: Clinical examination of the affected male showed typical features of LHON. In his unaffected mother slight peripapillary microangiopathy was found. Molecular analysis did not show any of the common LHON mutations. A nucleotide exchange was detected at position 14568 replacing a glycine by serine in the ND6 gene. This mutation was the only new mutation found within the entire protein and tRNA coding region of the patient’s mitochondrial genome. This novel mutation was also present in four non-affected maternal family members, but absent in 60 other LHON lineages and 175 unrelated controls. · Conclusion: The new mutation at nucleotide position 14568 lies in the close vicinity of other LHON-related mutations (np14459, np14484, np14498, np14596) within the evolutionarily most conserved region of the ND6 gene. Since no other mutation was detected throughout the mtDNA coding region and the new alteration was excluded in controls, our clinical and molecular genetic findings suggest that the novel point mutation at np14568 is responsible for LHON in this family.
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  • 7
    ISSN: 1432-1777
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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