cone-rod dystrophy 17

Cone-Rod Dystrophy 17: A Rare Eye Disorder

Cone-rod dystrophy 17 (CORD17) is a rare genetic eye disorder that affects the retina, leading to progressive vision loss. This condition is characterized by a decrease in sharpness of vision (visual acuity) and increased sensitivity to light.

Causes and Genetics

CORD17 is caused by genetic variations in the chromosome region 10q26 [5]. It is an autosomal dominant disorder, meaning that only one copy of the mutated gene is needed for the condition to manifest [9].

Symptoms and Progression

The first signs and symptoms of CORD17 often occur in childhood and include decreased visual acuity and increased sensitivity to light [3][6]. As the condition progresses, vision loss becomes more severe over time [2][4].

Characteristics and Diagnosis

CORD17 is a part of a larger group of cone-rod dystrophies, which are characterized by a decrease in vision typically occurring in the first two decades of life [6]. The diagnosis of CORD17 is based on clinical evaluation, genetic testing, and other diagnostic criteria.

References

• [2] Cone-rod dystrophy is a group of related eye disorders that causes vision loss, which becomes more severe over time.
• [3] The first signs and symptoms of cone-rod dystrophy, which often occur in childhood, are usually decreased sharpness of vision (visual acuity) and increased sensitivity to light.
• [4] Cone-rod dystrophy is a group of related eye disorders that causes vision loss, which becomes more severe over time.
• [5] Cone-rod dystrophy 17 is caused by genetic variations in the chromosome region 10q26.
• [6] Rod-Cone Dystrophy is a group of disorders characterized by a decrease in vision typically occurring in the first two decades of life.
• [7] A cone-rod dystrophy that has material basis in variation in the chromosome region 10q26.
• [8] Cone-rod dystrophy 17, 615163, Autosomal dominant, 2. TEXT. For a general phenotypic description and a discussion of genetic heterogeneity of cone-rod dystrophy...

Early Signs and Symptoms of Cone-Rod Dystrophy

Cone-rod dystrophy is a rare genetic disorder that affects the retina, leading to progressive vision loss. The first signs and symptoms of this condition often occur in childhood and can be quite subtle.

• Decreased Visual Acuity: One of the earliest signs of cone-rod dystrophy is decreased sharpness of vision (visual acuity) [1][3]. This can manifest as difficulty seeing objects clearly, even with glasses or contact lenses.
• Increased Sensitivity to Light: People with cone-rod dystrophy may experience increased sensitivity to light, which can lead to discomfort and eye strain [2][4].
• Color Vision Defects: Cone-rod dystrophies are characterized by defects in color vision, making it difficult for individuals to distinguish between different colors [5].
• Blurred Central Vision: As the condition progresses, blurred central vision can become a significant issue, affecting daily activities such as reading and driving [6].

Additional Symptoms

In addition to these early signs and symptoms, cone-rod dystrophy can also be identified by:

• Photophobia (sensitivity to light)
• Abnormalities in retinal imaging, such as bull's eye maculopathy and RPE atrophy [8]

It is essential for individuals with suspected cone-rod dystrophy to consult an ophthalmologist or genetic counselor for proper diagnosis and guidance.

Diagnostic Tests for Cone-Rod Dystrophy 17

Cone-rod dystrophy 17, a rare genetic disorder affecting the retina, can be diagnosed through various tests. Here are some diagnostic tests used to confirm the condition:

• Electrophysiology: A full-field electroretinogram (ERG) is the primary test for diagnosing cone-rod dystrophy 17 [7][12]. This test measures retinal activity directly and helps identify any abnormalities in the retina.
• Genetic Testing: Molecular genetic testing can help confirm the diagnosis by identifying mutations in one of the genes associated with cone/cone-rod dystrophy, such as RP1 [3][14].
• Clinical History and Examination: A thorough clinical history and examination are essential to rule out other conditions that may present similar symptoms. Fundus examination, autofluorescence imaging, optical coherence tomography (OCT), and full-field ERG can help confirm the diagnosis of cone-rod dystrophy 17 [8][9].
• Blood Tests: Blood is the preferred specimen type for genetic testing, and specimens should be received within 72 hours of collection if possible – maximum five days [4].

These diagnostic tests can help confirm the diagnosis of cone-rod dystrophy 17 and rule out other conditions that may present similar symptoms.

References:

[3] Mutations in more than 30 genes are known

Current Status of Drug Treatment for Cone-Rod Dystrophy 17

Unfortunately, there are currently no effective drug treatments available for cone-rod dystrophy 17 (CRD17). According to recent studies [6][10], the condition is characterized by a progressive decrease in vision, typically starting in early life, with normal or slightly impaired vision at birth. As the disease progresses, it leads to loss of color, central and peripheral vision, and eventually blindness.

Emerging Treatments

However, researchers are actively exploring emerging treatments that may assist in the future management of CRD17 [5]. These include gene therapies, which have shown promise in preclinical studies by improving rod photoreceptor cell vision and preserving cone cells in dogs with mutations in CNGB1 [8].

Gene Therapy Trials

One such gene therapy trial has been conducted on mice with CDHR1 mutations, using an adeno-associated virus serotype 8 (AAV8) to deliver healthy copies of CDHR1 to cells in the retina [11]. While this study is promising, it is essential to note that these findings are still in the early stages and require further research before any potential treatments can be translated into clinical practice.

Current Management

In the absence of effective drug treatments, management of CRD17 currently focuses on addressing specific symptoms as they arise. This may include using tinted lenses to alleviate visual discomfort [14]. However, it is crucial for individuals with CRD17 to consult with a genetic counselor to discuss their unique situation and potential treatment options.

References

[5] - There are currently no effective treatments available. A number of emerging treatments are being developed that may assist in the future. [6] - Currently, there is no treatment available for any form of cone-rod dystrophy. It is highly likely that patients with cone-rod dystrophies will ... [8] - Injection of the gene therapy into the eyes of dogs with mutations in CNGB1 improved rod photoreceptor cell vision, and helped preserve cone and ... [10] - Cone-rod dystrophy is a retinal disease that affects cells of your retina. It leads to progressive vision loss and, eventually, blindness. ... down. It eventually leads to loss of color, central and peripheral vision, and, ultimately, blindness. [11] - Approximately 200,000 people around the world have cone-rod dystrophy. In the study, mice with CDHR1 mutations were treated with a gene therapy that used an adeno-associated virus serotype 8 (AAV8), a safe, human-engineered virus, to deliver healthy copies of CDHR1 to cells in the retina. The gene therapy was delivered by a one-time, subretinal ...

Differential Diagnosis of Cone-Rod Dystrophy 17

Cone-rod dystrophy 17, like other forms of cone-rod dystrophies, requires a comprehensive differential diagnosis to rule out other hereditary cone disorders and pigmentary retinopathies. Here are some conditions that may be considered in the differential diagnosis:

• Achromatopsia and allied cone dysfunction syndromes: These are rare genetic disorders characterized by complete or near-complete color blindness, photophobia, and high sensitivity to light.
• Cone dystrophy: A group of inherited eye disorders that cause progressive vision loss due to degeneration of the cone cells in the retina.
• Stargardt disease: An inherited condition that causes progressive vision loss due to degeneration of the macula, which is responsible for central and color vision.

According to search result [3], there are more than 30 types of cone-rod dystrophy, each with its unique genetic cause and pattern of inheritance. Therefore, a thorough evaluation of the patient's medical history, family history, and ocular examination findings is essential to establish an accurate diagnosis.

In addition, other conditions such as Bardet-Biedl syndrome (search result [8]) may also be considered in the differential diagnosis, particularly if there are associated systemic features such as polydactyly, hypogonadism, obesity, and cognitive deficiency.

It is essential to note that a definitive diagnosis of cone-rod dystrophy 17 can only be made through genetic testing and ocular examination by an experienced ophthalmologist.

References:

• [3] Cone-rod dystrophy 17​​ There are more than 30 types of cone-rod dystrophy, which are distinguished by their genetic cause and their pattern of inheritance: ...
• [8] Differential diagnosis​​ Bardet-Biedl syndrome: AR cone–rod dystrophy with corneal thinning (uncommon), polydactyly, hypogonadism, obesity, cognitive deficiency, ...