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PubMed This is a summary of 3 peer-reviewed journal articles Updated
Ophthalmology

Why is ADOA More Common in Denmark? | Inciteful Med

At a Glance

Autosomal dominant optic atrophy (ADOA) is three times more common in Denmark (1 in 10,000) than globally (1 in 30,000) due to a genetic founder effect. This occurs because a specific OPA1 gene mutation was passed down from a common ancestor in a historically smaller, regional population.

In this answer

2 sections

01

The Founder Effect Explained

02

What This Means for Your Care

Autosomal dominant optic atrophy (ADOA) is a rare genetic condition that typically begins in early childhood, causing progressive vision loss such as color vision deficits and central vision blurring. Globally, the prevalence is estimated to be roughly 1 in 30,000 to 1 in 25,000, making it the most frequently diagnosed inherited optic neuropathy worldwide [1]. However, if you have heard that ADOA is more common in Denmark, that is entirely correct. In Denmark, the condition is significantly more prevalent, affecting approximately 1 in 10,000 individuals. This dramatic difference in how often the disease occurs is due to a genetic phenomenon known as a founder effect [2].

The Founder Effect Explained

A founder effect occurs when a new, smaller population is established by a very small number of individuals from a larger population. If one of those original “founders” carries a specific genetic mutation, that mutation can become much more common in the resulting population over generations simply by chance.

In the case of ADOA in Denmark, a specific historical mutation (often identified in research as a deletion in the OPA1 gene) occurred in a common ancestor centuries ago [2][3]. Because regional populations in the area were historically smaller and less mobile, this genetic change was passed down through generations, leading to a much higher concentration of people with the condition today compared to the rest of the world [3].

What This Means for Your Care

Understanding where the condition comes from can be comforting when tracing family history, but the biological mechanism of the disease remains similar regardless of your ancestry. The condition involves a gradual thinning of the nerve fibers in the eye that carry visual information to the brain (specifically, the retinal ganglion cells) [3]. Fortunately, while the vision loss is progressive, it rarely leads to complete blindness.

Managing ADOA

Whether your family originated in Denmark or elsewhere, the steps for managing the condition remain the same [1]:

  • Routine Monitoring: Regular comprehensive eye exams using Optical Coherence Tomography (OCT) are essential to measure and track the thinning of your retinal nerve fibers.
  • Genetic Testing: Identifying your specific OPA1 mutation can help your care team understand your individual risk factors and confirm a diagnosis.
  • Watching for ADOA+: Some genetic variants are associated with “ADOA plus” syndrome. Knowing your variant helps doctors monitor you for additional symptoms beyond vision loss, such as hearing impairment or muscle weakness.
  • Supportive Care: Connecting with low-vision rehabilitation specialists, learning to use low-vision aids, and getting audiology screenings will help ensure you maintain your independence and quality of life.

Common questions in this guide

Why is ADOA more common in Denmark?
ADOA is more common in Denmark due to a genetic phenomenon called the founder effect. Centuries ago, a common ancestor with a specific mutation in the OPA1 gene passed it down through a smaller, regional population, leading to a higher concentration of the condition today.
How rare is autosomal dominant optic atrophy globally?
Globally, ADOA is a rare condition that affects approximately 1 in 25,000 to 1 in 30,000 people. However, in Denmark, the prevalence is much higher, affecting about 1 in 10,000 individuals.
What are the symptoms of ADOA?
The most common symptoms include progressive vision loss, difficulty distinguishing colors, and central vision blurring. These changes usually begin in early childhood and are caused by the gradual thinning of nerve fibers in the eye.
What is ADOA plus syndrome?
ADOA plus syndrome occurs when specific genetic variants cause additional symptoms beyond vision loss. People with ADOA plus may also experience hearing impairment or muscle weakness, which is why genetic testing and comprehensive monitoring are important.
How do doctors monitor ADOA progression?
Doctors track the condition using regular comprehensive eye exams and Optical Coherence Tomography (OCT) scans. These imaging tests allow your eye care team to precisely measure the thinning of your retinal nerve fibers over time.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Given my diagnosis of ADOA, does my genetic testing report show a specific 'founder mutation,' or a different variant of the OPA1 gene?
  2. 2.What specific imaging tests, such as an OCT scan, will you use to monitor the progression of my optic nerve thinning?
  3. 3.Should my immediate family members undergo genetic testing or baseline eye exams even if they aren't currently experiencing vision problems?
  4. 4.Based on my specific genetic variant, are there any extra-ocular symptoms (like hearing loss associated with ADOA+) that I should be watching for?
  5. 5.Can you refer me to a low-vision specialist or occupational therapist to help me find the right daily support tools?

Questions For You

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Related questions

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References

References (3)
  1. 1

    ATPase Domain AFG3L2 Mutations Alter OPA1 Processing and Cause Optic Neuropathy.

    Caporali L, Magri S, Legati A, et al.

    Annals of neurology 2020; (88(1)):18-32 doi:10.1002/ana.25723.

    PMID: 32219868
  2. 2

    Genotype-phenotype heterogeneity of ganglion cell and inner plexiform layer deficit in autosomal-dominant optic atrophy.

    Rönnbäck C, Nissen C, Almind GJ, et al.

    Acta ophthalmologica 2015; (93(8)):762-6 doi:10.1111/aos.12835.

    PMID: 26385429
  3. 3

    Dissociation of Pupillary Post-Illumination Responses from Visual Function in Confirmed OPA1 c.983A > G and c.2708_2711delTTAG Autosomal Dominant Optic Atrophy.

    Nissen C, Rönnbäck C, Sander B, et al.

    Frontiers in neurology 2015; (6()):5 doi:10.3389/fneur.2015.00005.

    PMID: 25699009

This page explains the prevalence and genetics of ADOA for educational purposes only and does not replace professional medical advice. Always consult your ophthalmologist or genetic counselor regarding your specific diagnosis and care plan.

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