Posterior Reversible Encephalopathy Syndrome in a Leber Hereditary Optic Neuropathy Patient With Mitochondrial DNA 11778G>A Point Mutation

A Typical Case Presentation with Spontaneous Visual Recovery in Patient Diagnosed with Leber Hereditary Optic Neuropathy due to Rare Point Mutation in MT-ND4 Gene (m.11253T>C) and Literature Review

Leber hereditary optic neuropathy (LHON) is one of the most common inherited mitochondrial optic neuropathies, caused by mitochondrial DNA (mtDNA) mutations. Three most common mutations, namely m.11778G>A, m.14484T>G and m.3460G>A, account for the majority of LHON cases. These mutations lead to mitochondrial respiratory chain complex I damage. Typically, LHON presents at the 15–35 years of age with male predominance. LHON is associated with severe, subacute, painless bilateral vision loss and account for one of the most common causes of legal blindness in young individuals. Spontaneous visual acuity recovery is rare and has been reported in patients harbouring m.14484T>C mutation. Up to date LHON treatment is limited. Idebenone has been approved by European Medicines Agency (EMA) to treat LHON. However better understanding of disease mechanisms and ongoing treatment trials are promising and brings hope for patients. In this article we report on a patient diagnosed with LHON harbouring rare m.11253T>C mutation in MT-ND4 gene, who experienced spontaneous visual recovery. In addition, we summarise clinical presentation, diagnostic features, and treatment.

Mitochondrial disorders of the retinal ganglion cells and the optic nerve

OBJECTIVES

To summarise and discuss recent findings and future perspectives concerning mitochondrial disorders (MIDs) affecting the retinal ganglion cells and the optic nerve (mitochondrial optic neuropathy. MON).

METHOD

Literature review.

RESULTS

MON in MIDs is more frequent than usually anticipated. MON may occur in specific as well as non-specific MIDs. In specific and non-specific MIDs, MON may be a prominent or non-prominent phenotypic feature and due to mutations in genes located either in the mitochondrial DNA (mtDNA) or the nuclear DNA (nDNA). Clinically, MON manifests with painless, bilateral or unilateral, slowly or rapidly progressive visual impairment and visual field defects. In some cases, visual impairment may spontaneously recover. The most frequent MIDs with MON include LHON due to mutations in mtDNA-located genes and autosomal dominant optic atrophy (ADOA) or autosomal recessive optic atrophy (AROA) due to mutations in nuclear genes. Instrumental investigations for diagnosing MON include fundoscopy, measurement of visual acuity, visual fields, and color vision, visually-evoked potentials, optical coherence tomography, fluorescein angiography, electroretinography, and MRI of the orbita and cerebrum. In non-prominent MON, work-up of the muscle biopsy with transmission electron microscopy may indicate mitochondrial destruction. Treatment is mostly supportive but idebenone has been approved for LHON and experimental approaches are promising.

CONCLUSIONS

MON needs to be appreciated, requires extensive diagnostic work-up, and supportive treatment should be applied although loss of vision, as the most severe outcome, can often not be prevented.

Leber's hereditary optic neuropathy is multiorgan not mono-organ

Leber's hereditary optic neuropathy (LHON) is a maternally inherited mitochondrial disorder with bilateral loss of central vision primarily due to mitochondrial DNA (mtDNA) mutations in subunits of complex I in the respiratory chain (primary LHON mutations), while other mtDNA mutations can also be causative. Since the first description, it is known that LHON is not restricted to the eyes but is a multisystem disorder additionally involving the central nervous system, ears, endocrinological organs, heart, bone marrow, arteries, kidneys, or the peripheral nervous system. Multisystem involvement may start before or after the onset of visual impairment. Involvement of organs other than the eyes may be subclinical depending on age, ethnicity, and possibly the heteroplasmy rate of the responsible primary LHON mutation. Primary LHON mutations may rarely manifest without ocular compromise but with arterial hypertension, various neurodegenerative diseases, or Leigh syndrome. Patients with LHON need to be closely followed up to detect at which point organs other than the eyes become affected. Multiorgan disease in LHON often responds more favorably to symptomatic treatment than the ocular compromise.