Disease spotlight: LHON

Leber’s hereditary optic neuropathy (LHON) is a rare, progressive, hereditary condition that leads to blindness in young adults.

The disease is caused by a genetic mutation which leads to the loss of function in small components in cells at the back of the eye call mitochondria. Defective mitochondria cannot properly use energy and so the cells in the eye stop working. This leads to the disease’s characteristic symptom of progressive vision loss.

The genetic mutation responsible for LHON is passed down by the mother 100% of the time. However, not all people with the mutation will exhibit symptoms in during their lifetime. Fathers can carry the gene but do not pass it on to their children.

Incidence

• LHON affects approximately two in every 100,000 people in Europe and is most commonly diagnosed in people aged 27-34.

Symptoms

• LHON causes a severe, painless loss of central vision, initially in one eye. The same symptoms are experienced in the second eye typically within weeks or a few months later.
• Both sharpness of vision and colour worsen as the disease progresses.
• In rare cases, people may regain their central vision over time. However, vision loss will be permanent in the majority of people with the condition.
• Around 80% of LHON patients are deemed legally blind within one year of the onset of symptoms.

Diagnosis

• The process of diagnosis can differ between countries and is highly variable depending on a doctor’s awareness of the disease.
• Typically, a blood test is performed to look for mutations related to LHON.
• Tests will be performed to eliminate other potential causes of vision loss, such as eye examinations, MRI and CT scans, and an electroretinogram (ERG).

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