On this page
Autosomal dominant optic atrophy (Kjer)
Kjer type optic atrophy causes gradual vision impairment, typically starting in childhood or adolescence. It primarily affects the sharpness of central vision, impacting daily activities like reading or recognising faces, and it is inherited in an autosomal dominant pattern.
Available at Jeen Health
Clinical tests that include this
Overview
Autosomal dominant optic atrophy, often known as Kjer type optic atrophy, is a genetic disorder that affects the optic nerve. The optic nerve transmits visual information from the eye to the brain. In Kjer type optic atrophy, the nerve cells that make up the optic nerve gradually deteriorate, leading to progressive vision loss [PMID:24151283]. This condition is typically diagnosed in childhood or early adulthood, and its severity can vary significantly among affected individuals, even within the same family.
While Kjer type optic atrophy is considered a rare condition, it is thought to be one of the most common inherited forms of optic neuropathy. Prevalence estimates suggest it affects approximately 1 in 12,000 to 1 in 50,000 people in the UK. The vision loss is usually gradual and affects both eyes, though one eye may be more affected than the other. Importantly, the condition does not typically lead to complete blindness.
Symptoms & clinical features
The primary symptom of Kjer type optic atrophy is a reduction in visual acuity, meaning the sharpness of vision. This often manifests as difficulty with detailed tasks like reading, writing, or recognising faces. The vision loss typically begins subtly and progresses slowly over many years [PMID:17918077]. Most affected individuals experience mild to moderate vision impairment, but some can have more severe vision loss.
Changes in colour vision, particularly an inability to distinguish between blue and yellow shades (blue-yellow dyschromatopsia), are also common features of Kjer type optic atrophy. Some individuals may develop a 'scotoma,' which is a blind spot in their central visual field. While rare, other neurological symptoms such as hearing loss, muscle weakness, or problems with balance and coordination have occasionally been reported, particularly in individuals with certain genetic changes, indicating some variability in presentation.
Video: Genetics 101
Affected organs
Kjer type optic atrophy primarily affects the eyes, specifically the optic nerves. The optic nerves are bundles of nerve fibres that carry visual signals from the retina at the back of the eye to the brain, where these signals are interpreted as images. In this condition, the cells within the optic nerve, known as retinal ganglion cells, gradually degenerate, which impairs this signal transmission.
Beyond the optic nerves, in a small proportion of individuals, other organ systems may be mildly affected, leading to a broader range of symptoms. These can include the auditory system, potentially causing some degree of hearing impairment, and the nervous system, which might result in mild peripheral neuropathy (nerve damage outside the brain and spinal cord) or ataxia (problems with balance and coordination).
Risks & severity
The severity of Kjer type optic atrophy varies widely, even amongst members of the same family who have the same genetic change. Vision loss typically begins in early childhood or adolescence, often between the ages of 4 and 6 years, but it can also present later in life, sometimes in adulthood [PMID:17918077]. The progression of vision loss is generally slow and continuous over many years.
While the condition does not usually cause complete blindness, many individuals will have lifelong visual impairment that requires visual aids and support. The impact on daily life can range from subtle difficulties with detailed tasks to significant challenges with activities like driving or certain occupations. Regular ophthalmological assessments are important to monitor vision changes and provide appropriate support.
Genetic causes
Kjer type optic atrophy is most commonly caused by changes (pathogenic variants) in the OPA1 gene. The OPA1 gene provides instructions for making a protein found primarily in mitochondria, which are the 'powerhouses' of cells. This OPA1 protein plays a crucial role in maintaining the structure and function of mitochondria, particularly in processes like mitochondrial fusion (when mitochondria join together) and energy production.
Pathogenic variants in OPA1 can disrupt the normal function of the OPA1 protein, leading to mitochondrial dysfunction. Nerve cells, especially those in the optic nerve, require a large amount of energy to function correctly. When mitochondria are not working efficiently due to a faulty OPA1 protein, the optic nerve cells can become damaged and ultimately die, leading to progressive vision loss. Other genes are rarely associated with autosomal dominant optic atrophy, but OPA1 is by far the most common cause [PMID:24151283].
- OPA1 OPA1 mitochondrial dynamin like GTPase
Inheritance pattern
Kjer type optic atrophy follows an autosomal dominant pattern of inheritance. This means that an individual only needs to inherit one copy of the altered OPA1 gene from one parent to develop the condition. If one parent has Kjer type optic atrophy, each of their children has a 50% chance of inheriting the altered gene and therefore developing the condition, regardless of the child's sex.
The condition can sometimes appear in individuals with no family history, which occurs when a new (de novo) genetic change arises spontaneously. It's important for affected individuals and their families to discuss the inheritance pattern with a genetic counsellor to understand the risks for future generations and other family members.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
Diagnosis & testing
Diagnosis of Kjer type optic atrophy typically involves a comprehensive eye examination by an ophthalmologist, including assessment of visual acuity, visual fields, and colour vision. An eye care professional may observe pallor (paleness) of the optic disc, which is the part of the optic nerve visible at the back of the eye, indicating nerve damage.
Confirmation of the diagnosis is usually made through genetic testing, which can identify pathogenic variants in the OPA1 gene. Genetic testing for inherited eye conditions, including Kjer type optic atrophy, is available through the NHS Genomic Medicine Service (GMS) using specific R-codes, such as R25 (inherited retinal disease) or R101 (inherited optic neuropathy). Referral for genetic testing is typically made by an ophthalmologist or a clinical geneticist.
Management & lifestyle
There is currently no cure for Kjer type optic atrophy, and treatments that reverse optic nerve damage are not available. Management focuses on supporting individuals to optimise their remaining vision and adapt to their visual impairment. This may include regular monitoring of vision, prescription of appropriate optical aids such as glasses or magnifiers, and consideration of assistive technologies.
Patients are typically managed through ophthalmology services within the NHS. Genetic counselling is an important part of the care pathway, providing information about the condition, its inheritance pattern, and support for family planning. Low vision services can offer practical advice and aids for daily living. In cases where additional symptoms like hearing loss are present, multidisciplinary care involving other specialists may be required. Individuals are advised to maintain a healthy lifestyle, as mitochondrial health may be influenced by diet and exercise, though specific interventions for OPA1-related optic atrophy are still under research.
UK care pathway
For individuals in the UK suspected of having Kjer type optic atrophy, the care pathway typically begins with a referral to an ophthalmologist for specialist assessment. If an inherited optic neuropathy is suspected, the ophthalmologist may then refer to a Clinical Genetics service for genetic counselling and consideration of genetic testing. Genetic testing for this condition is available through the NHS Genomic Medicine Service using relevant R-codes, such as R25 or R101, which cover testing for inherited retinal diseases and optic neuropathies respectively. Genetic counsellors play a crucial role in explaining the genetic basis of the condition, its inheritance, and implications for family members.
Frequently asked questions
What is the typical age for vision loss to start in Kjer type optic atrophy?
Vision loss in Kjer type optic atrophy often begins in early childhood, commonly between the ages of 4 and 6 years. However, the onset can vary, with some individuals experiencing symptoms later in adolescence or even adulthood.
Will Kjer type optic atrophy cause complete blindness?
Kjer type optic atrophy typically does not lead to complete blindness. While it causes progressive vision loss and can result in significant visual impairment, most affected individuals retain some level of vision throughout their lives.
Can Kjer type optic atrophy be treated?
Currently, there is no cure for Kjer type optic atrophy, and no treatments are available to reverse the damage to the optic nerve. Management focuses on supporting vision with aids like glasses or magnifiers and adapting to visual impairment.
If I have Kjer type optic atrophy, what is the chance my children will inherit it?
Kjer type optic atrophy is inherited in an autosomal dominant manner. If you have the condition, each of your children has a 50% chance of inheriting the altered gene and therefore developing the condition.
Is there a specific genetic test for Kjer type optic atrophy?
Yes, genetic testing can identify pathogenic variants in the OPA1 gene, which is the most common cause of Kjer type optic atrophy. This testing is available through the NHS Genomic Medicine Service.
References
- Newman NJ, Biousse V. Hereditary optic neuropathies. Eye (London, England). 2004. PMID: 15534600
- Eliott D, Traboulsi EI, Maumenee IH. Visual prognosis in autosomal dominant optic atrophy (Kjer type). American journal of ophthalmology. 1993. PMID: 8442497