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Inherited Optic Neuropathies
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Hui-Chen Cheng, Jared Ching, An-Guor Wang, Patrick Yu-Wai-Man
Patients with inherited optic neuropathies tend to present with bilateral, usually symmetrical, visual loss. The onset of visual deterioration can be subacute or insidious and the age of onset varies depending on the underlying cause. In severe and early-onset cases, patients can also develop nystagmus (3). Sequential visual loss is more commonly observed in patients with Leber hereditary optic neuropathy (LHON). In the initial stages of investigation, it is important to exclude other causes of a bilateral simultaneous or sequential optic neuropathy (3). Neuroimaging, for example, may be indicated to exclude compressive, infiltrative or inflammatory pathologies affecting the anterior visual pathway (4). Another important group to consider in the differential diagnosis is a primary retinal dystrophy masquerading as an optic neuropathy since the retinal findings may be subtle with more attention being paid to the coexisting pallor of the optic disc (3). Visual electrodiagnostic testing can be helpful in these cases to help distinguish retinal dystrophies from optic neuropathies (3, 4).
Clinical Perspectives on Gene Therapy for Retinal and Eye Diseases
Published in Yashwant Pathak, Gene Delivery, 2022
Devika S. Joshi, Gaurav M. Karve, Shrikant D. Joshi
Leber’s hereditary optic neuropathy (LHON) is a common inherited mitochondrial disorder. It is characterized by the degeneration of the optic nerves, leading to vision loss. The major mutations in the mitochondrial genes ND1, ND4, and ND6 of LHON subjects are found to increase the oxidative stress experienced by the optic nerve cell, thereby leading to nerve cell damage and vision loss.
Neurogenetics
Published in John W. Scadding, Nicholas A. Losseff, Clinical Neurology, 2011
Sonia Gandhi, Sarah Tabrizi, Nicholas Wood
MERRF (myoclonus epilepsy with ragged red fibres) is caused by the A8344G mutation in the lysine tRNA gene. MERRF has been described earlier. Of note, the 8344 mutation may also cause Leigh syndrome. NARP (neurogenic weakness, ataxia and retinitis pigmentosa) has been described elsewhere, and is caused by a T8993G mutation in the ATPase 6 gene. LHON (Leber’s hereditary optic neuropathy) is characterized by subacute loss of vision bilaterally. Several mtDNA mutations can cause LHON, although the three most common are 11778 (ND4), 3460 (ND1) and 14484 (ND6). The age of onset is in the second to third decade and the penetrance is 40 per cent in males and only 10 per cent in females.
Neuro-Ophthalmic Literature Review
Published in Neuro-Ophthalmology, 2020
David A. Bellows, Noel C.Y. Chan, John J. Chen, Hui-Chen Cheng, Peter W MacIntosh, Jenny A. Nij Bijvank, Michael S. Vaphiades
The authors aimed to study the demographics of Leber’s hereditary optic neuropathy (LHON) using an international database of people affected by LHON. The www.LHON.org website was created in 2009 with voluntary registration by people affected by LHON. Data were collected by interview for all the participants. People who were not genetically tested, were not on a known LHON pedigree, or were unable to provide accurate information regarding mutation or age of symptom onset, were excluded from this study. One thousand five hundred and seventeen people affected by LHON with a known pathogenic genetic mutation were enrolled. The authors found a 3:1 male:female ratio. In addition, the male:female ratio was approximately 1:1 for those below the age of 5 and after the age of 45. Male patients had a peak onset time between ages 14–26. For females, disease onset occurred across all age groups without a significant peak of onset age. They also found that 10% of individuals had disease onset after the age of 50. The authors suggested that women carrying an LHON mutation are at higher risk of losing vision than has been generally expected. Counselling about LHON should be offered to all maternal bloodline relatives for both genders, as they are at risk of visual loss.
Neuro-Ophthalmic Literature Review
Published in Neuro-Ophthalmology, 2019
David Bellows, Noel Chan, John Chen, Hui-Chen Cheng, Peter MacIntosh, Sui Wong, Michael Vaphiades
The authors enrolled 22 patients with a molecularly confirmed diagnosis of Leber‘s hereditary optic neuropathy (LHON) with mean disease duration of 18.8 years, and 25 age-similar controls. They aimed to study the differences of Patten Electroretinogram (PERG) and Visual Evoked Potential (VEP) between LHON and normal controls, and they also compared the longitudinal changes during 12-months follow-up in these chronic LHON patients. At baseline, LHON eyes showed a significant reduction in amplitude of PERG compared to controls. In the LHON group, the mean amplitude of PERG did not differ between baseline, 6- and 12-months follow-up. Regarding VEP, LHON eyes showed significantly increased peak time and reduced amplitude compared to controls. During longitudinal follow-up, the mean peak time and amplitude of VEP did not change significantly in LHON patients. The authors suggested that electrophysiology studies should be considered when attempts for treatments are proposed in chronic LHON.
Never too old: late‐onset Leber hereditary optic neuropathy
Published in Clinical and Experimental Optometry, 2018
Stephen J Vincent, Kirsty A Lowe, Cindy S Monsour
Leber hereditary optic neuropathy‐related visual loss occurs prior to or during the fifth decade in 95 per cent of affected patients.2002 While several isolated case reports and case series2014 have described the features of late‐onset LHON (onset after 50 years), this appears to be the most delayed onset of LHON‐related visual loss in a woman (age 77 years) in the published literature. This is a particularly rare clinical presentation given the 5:1 predilection to affected males in late‐onset cohorts.2014 Numerous environmental factors have been hypothesised to trigger acute late‐onset visual loss in LHON carriers, most notably, trauma, smoke inhalation, excessive alcohol consumption, anaemia and vitamin B12 deficiency. Although it is impossible to identify a single precipitating factor with certainty, vitamin B12 deficiency may have initiated visual loss in this patient, despite long‐term supplementation, given the absence of any history of ocular or head trauma or history of smoking or alcohol abuse.