congenital stationary night blindness 1B

Congenital Stationary Night Blindness 1B (CSNB1B) Description

Congenital stationary night blindness 1B (CSNB1B) is a rare genetic disorder that affects the retina, specifically impairing the ability to see in low light conditions. People with this condition typically have difficulty seeing and distinguishing objects in dimly lit environments.

Key Features:

• Night Blindness: The most common symptom of CSNB1B is night blindness, which makes it difficult for individuals to see in low light conditions.
• Retinal Disorder: CSNB1B is a disorder of the retina, specifically affecting the photoreceptors that detect light and color.
• Non-Progressive: Unlike other retinal disorders, CSNB1B is non-progressive, meaning that vision loss does not worsen over time.

Genetic Cause: CSNB1B is caused by mutations in the GRM6 gene on chromosome 5q35. This genetic mutation affects the normal functioning of photoreceptors in the retina, leading to impaired night vision.

References:

• [5] states that CSNB1B is caused by homozygous or compound heterozygous mutation in the GRM6 gene.
• [7] describes CSNB1B as a disorder of the retina that affects people's ability to see and distinguish objects in low light conditions.

Note: The information provided is based on the search results and may not be an exhaustive description of the condition.

Common Signs and Symptoms of Congenital Stationary Night Blindness 1B

Congenital stationary night blindness 1B (CSNB1B) is a rare genetic disorder that affects the retina, causing difficulty seeing in low light conditions. The primary symptom of CSNB1B is night blindness, which means individuals with this condition have trouble seeing and distinguishing objects in dimly lit environments.

• Night Blindness: People with CSNB1B may struggle to see road signs at night, identify stars in the sky, or navigate through dark spaces.
• Reduced Visual Acuity: In addition to night blindness, individuals with CSNB1B often experience a mild to moderate reduction in visual acuity, making it difficult for them to read, watch TV, or perform other daily activities that require clear vision.
• Nearsightedness (Myopia): Many people with CSNB1B also develop nearsightedness, which means they can see objects up close but struggle to see distant objects clearly.
• Involuntary Eye Movements: Some individuals with CSNB1B may experience involuntary eye movements, such as nystagmus, which can be a sign of the condition.

Other Possible Symptoms

While not all people with CSNB1B will exhibit these symptoms, some may also experience:

• Increased Sensitivity to Light (Photophobia): Some individuals with CSNB1B may feel uncomfortable or sensitive to light, especially in bright environments.
• Fundus Abnormalities: In some cases, the retina of individuals with CSNB1B may appear abnormal when viewed through an ophthalmoscope.

References

[4] [5] [6] [11]

Based on the provided context, here are the diagnostic tests for Congenital Stationary Night Blindness (CSNB) 1B:

• Electroretinogram (ERG): This test measures the function of the retina and is used to diagnose CSNB. The types of CSNB are distinguished by their genetic causes and by the results of an ERG [6].
• Genetic testing: Genetic testing can be used to confirm a diagnosis of CSNB 1B. A clinical molecular genetics test for Congenital stationary night blindness 1B is available, which includes sequence analysis of the entire coding region, Next-Generation (NGS)/Massively parallel sequencing (MPS) with CNV detection included [11].
• Full-field electroretinograms (ERG): Diagnosis of CSNB relies on full-field ERG and genetic testing to confirm the diagnosis [3].

It's worth noting that a clinical resource is available that provides information about Congenital stationary night blindness, including its clinical features, available genetic tests from US and labs around the world, and links to practice guidelines and authoritative resources like GeneReviews [12].

Differential Diagnosis of Congenital Stationary Night Blindness 1B

Congenital stationary night blindness (CSNB) 1B is a rare genetic disorder that affects the retina, causing night blindness. When diagnosing CSNB 1B, it's essential to consider other conditions that may present similar symptoms. Here are some differential diagnoses for CSNB 1B:

• Cone-rod dystrophy: This condition can share a similar appearance with CSNB 1B but has a progressive clinical course [3]. Cone-rod dystrophy is characterized by the degeneration of cone and rod photoreceptors, leading to visual loss.
• Stargardt disease: This is an inherited disorder that affects the macula, causing progressive vision loss. Stargardt disease can be mistaken for CSNB 1B due to its similar presentation [9].
• Retinitis pigmentosa (RP): RP is a group of genetic disorders that affect the retina, leading to night blindness and progressive visual loss. Female carriers of RP can present with symptoms similar to CSNB 1B [9].
• Juvenile retinoschisis: This is a rare inherited disorder that affects the retina, causing vision loss and retinal detachment. Juvenile retinoschisis can be mistaken for CSNB 1B due to its similar presentation [9].
• Progressive cone dystrophy: This condition is characterized by the degeneration of cone photoreceptors, leading to progressive visual loss. Progressive cone dystrophy can be mistaken for CSNB 1B due to its similar presentation [3].

It's essential to note that a comprehensive diagnosis of CSNB 1B requires a thorough evaluation, including full-field electroretinograms (ERG) and genetic testing.

References:

[3] - Cone-rod dystrophy: Early cone-rod dystrophy may share a similar appearance but has a progressive clinical course. [9] - The differential diagnosis includes Stargardt disease, RP in female carriers, juvenile retinoschisis, and progressive cone dystrophy (see these terms).