Frequently asked questions

  • LHON is a rare genetic eye condition that runs in families and severely impacts visual acuity.Footnote1 Symptoms in LHON begin with sudden loss of sight and painless blurring and clouding of central vision in one or both eyes.Footnote2 It results from cell dysfunction, and eventually cell death in the optic nerve that relays visual signals from the eye to the brain.Footnote3

  • LHON begins with the following symptoms:
    a. Sudden vision issues in one or both eyes
    b. Painless blurring in the centre of the eye
    c. Blurring of vision
    d. Loss of sharpness
    e. Loss of colour vision

  • If you think you might have LHON, do not wait for symptoms to get worse. Look for an LHON specialist such as an ophthalmologist. If you cannot approach an ophthalmologist directly, talk to your GP about your suspicions around LHON to speed up the diagnosis. They can refer you to an eye care specialist for further management of your condition.

  • LHON is a rare genetic condition that leads to symptoms such as sudden sight loss and blurred vision. These are caused by mutations in the mitochondrial DNA. A mother with an LHON mutation passes it on to all her children. However, a father who has LHON cannot pass it on to any of his children. This is because the mitochondria for the developing baby come from the mother’s egg cells and not the father’s sperm cells.

    A second form of LHON mutation in a nuclear encoded gene, DNAJC30, has also been established—described as an autosomal recessive mode of inheritance for LHON (arLHON).Footnote6

  • LHON is a progressive disease leading to severe vision impairment. Most patients with LHON become legally blind. Speak to an ophthalmologist if you have symptoms or a family history of LHON. They can guide you on the possible management options, follow-up and low vision rehabilitation.

  • People without a family history of LHON are known to develop the condition.Footnote4 Around one in three cases appears to be sporadic with no definitive family history.Footnote7 In addition, a second form of LHON mutation in a nuclear encoded gene, DNAJC30, has also been established—described as an autosomal recessive mode of inheritance for LHON (arLHON).Footnote6

    If the ophthalmologic assessments and molecular genetic testing leave any uncertainty about the diagnosis of LHON, further investigations are appropriate to exclude other potentially reversible causes of bilateral optic neuropathy and to allow for prompt management of the condition before visual loss may become irreversible.Footnote4

  • Molecular genetic testing approaches can include a combination of gene-targeted testing methods such as, targeted mtDNA analysis for pathogenic variants, multigene panel test, and mitochondrial sequencing.Footnote4,Footnote8–10

    In the absence of family history, LHON inherited by nuclear mutations (arLHON) can be diagnosed through nuclear-mitochondrial gene screening.Footnote6,Footnote8

  • The threat of acquiring LHON never goes away but you can avoid certain lifestyle factors to reduce the risk.Footnote4 Those with an LHON mutation are advised to stop smoking, moderate their alcohol intake and avoid certain medications.Footnote4

    Men are four to five times more likely to be affected by LHON than women.Footnote4 The first signs of vision loss usually appear between the ages of 15 and 35 years.5 In rare cases, symptoms can occur between 2 and 87 years of age.5 LHON affects women more commonly during the menopause years.Footnote11

  • A mother with an LHON mutation passes it on to all her children. However, a father who has LHON cannot pass it on to any of his children. This is because the mitochondria for the developing baby come from the mother’s egg cells and not the father’s sperm cells. So, any mutations in the mitochondria can only be inherited maternally.

    However, around one in three cases also appears to be sporadic with no definitive family history.Footnote7 In addition, a second form of LHON mutation in a nuclear encoded gene, DNAJC30, has also been established—described as an autosomal recessive mode of inheritance for LHON (arLHON).Footnote6

  • For patients and their families, LHON can come as a shock. However, most of the affected people adjust to their new level of visual functioning within a few years after the first symptoms of LHON appear.Footnote12

    There are a number of patient advocacy groups and online support groups for patients with LHON.

  • Autosomal recessive inheritance: This is one of the ways a genetic trait or condition can be passed down from parent to child. In autosomal recessive inheritance, the affected individual inherits one copy of a mutated gene from each parent for a genetic condition to occur.6,13

    DNA: This is the hereditary material located inside the cells in our body and contains the information needed for that cell, and our body, to develop and function. This information is passed from parents to their children through DNA.13

    Maternal inheritance: When a mutation is passed from mothers, but not from fathers, to their children.4,13

    Mitochondria: These are small structures (organelles) that exist inside our cells and generate the energy needed for that cell to function.14

    Mitochondrial DNA (mtDNA): DNA that is found in the mitochondria.13

    Mitochondrial sequencing: A technique that can help analyse mitochondrial DNA and identify disease-related mutations which could be missed by other methods.4,13

    Mutations: The genes in our body act as instructions to make molecules called proteins. Changes in a gene are called mutations. These prevent one or more of the proteins to do their jobs causing disease.13

    Nuclear-encoded gene: A gene that is found in the cell nucleus.13

    Nucleus: The structure inside our cells that contains most of our DNA.13,14

    Optic nerve: The nerve that carries visual information from the retina to the brain.15

    Pathogenic variant: This refers to a mutated gene that increases an individual’s chance of developing a specific disease or disorder.4,13

    1. Theodorou-Kanakari A, et al. Adv Ther. 2018;35:1510–18.

    2. Carelli V, et al. Eur Ophthalmic Rev. 2019;13(Suppl 52).

    3. Carelli V, et al. Hum Mol Genet. 2017:26;139–50.

    4. Yu-Wai-Man P and Chinnery PF. Leber Hereditary Optic Neuropathy. GeneReviews® [Internet]. 2021. Available at: https:// www.ncbi.nlm.nih.gov/books/NBK1174/. Accessed: March 2023.

    5. Fraser JA, et al. Surv Ophthalmol. 2010; 55:299–334.

    6. Stenton SL, et al. J Clin Invest. 2021:15;131(6):e138267.

    7. Karaarslan C. Adv Ther. 2019:36;3299–307.

    8. NHS Commissioning Board, 2013. Rare mitochondrial disorders service (all ages). Service specification 13/S(HSS)/h. Available at: https://www.england.nhs.uk/wp-content/uploads/2013/06/e13-rare-mitoch-dis.pdf. Accessed: March 2023.

    9. NHS England. National Genomic Test Directory. Testing Criteria for Rare and Inherited Disease. June 2023. Available at: www.england.nhs.uk/wp-content/uploads/2018/08/Rare-and-inherited-disease-eligibility-criteria-version-5.2.pdf. Accessed: June 2023.

    10. Genomics England PanelApp. Available at: https://panelapp.genomicsengland.co.uk/panels/530/. Accessed: March 2023.

    11. Asanad S and Karanjia R. StatPearls Publishing; 2021. PMID: 32809476.

    12. Kirkman MA, et al. IOVS. 2009;50: 3112–15.

    13. Genetic Alliance. The New York-Mid-Atlantic Consortium for Genetic and Newborn Screening Services. Understanding Genetics: A New York, Mid-Atlantic Guide for Patients and Health Professionals. Washington (DC): Genetic Alliance; 2009. Available at: https://www.ncbi.nlm.nih.gov/books/NBK115558/. Accessed: March 2023.

    14. Meyersen C, et al. Clin Ophthal. 2015;9:1165–76.

    15. Carelli V, et al. Biochimica et Biophysica Acta (BBA) – Bioenergetics. 2009;1787(5):518–28.

Disclaimer: The information on this website is intended only to provide knowledge of Leber’s hereditary optic neuropathy (LHON). This information should not be used in place of advice from a healthcare professional. Please contact your doctor for advice. This website has been produced by Chiesi Pharmaceuticals. The website has been developed in accordance with industry and legal standards to provide information for the general public about LHON. Chiesi Pharmaceuticals makes every reasonable effort to include accurate and current information. However, the information provided in this website is not exhaustive.