Autosomal recessive congenital stationary night blindness

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Autosomal recessive congenital stationary night blindness is a disorder of the retina, which is the specialized tissue at the back of the eye that detects light and color. People with this condition typically have difficulty seeing and distinguishing objects in low light (night blindness). For example, they may not be able to identify road signs at night or see stars in the night sky. They also often have other vision problems, including loss of sharpness (reduced acuity), nearsightedness (myopia), involuntary movements of the eyes (nystagmus), and eyes that do not look in the same direction (strabismus).

The vision problems associated with this condition are congenital, which means they are present from birth. They tend to remain stable (stationary) over time.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in several genes can cause autosomal recessive congenital stationary night blindness. Each of these genes provide instructions for making proteins that are found in the retina. These proteins are involved in sending (transmitting) visual signals from cells called rods, which are specialized for vision in low light, to cells called bipolar cells, which relay the signals to other retinal cells. This signaling is an essential step in the transmission of visual information from the eyes to the brain.

Mutations in two genes, GRM6 and TRPM1, cause most cases of this condition. These genes provide instructions for making proteins that are necessary for bipolar cells to receive and relay signals. Mutations in other genes involved in the same bipolar cell signaling pathway are likely responsible for a small percentage of cases of autosomal recessive congenital stationary night blindness.

Gene mutations that cause autosomal recessive congenital stationary night blindness disrupt the transmission of visual signals between rod cells and bipolar cells or interfere with the bipolar cells' ability to pass on these signals. As a result, visual information received by rod cells cannot be effectively transmitted to the brain, leading to difficulty seeing in low light. The cause of the other vision problems associated with this condition is unclear. It has been suggested that the mechanisms that underlie night blindness can interfere with other visual systems, causing myopia, reduced visual acuity, and other impairments.

Some people with autosomal recessive congenital stationary night blindness have no identified mutation in any of the known genes. The cause of the disorder in these individuals is unknown.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Autosomal recessive congenital stationary night blindness is likely a rare disease; however, its prevalence is unknown.

Understanding terms used in the source

These definitions explain medical words used above. A definition is not evidence that another condition is present, and it does not predict how a symptom will develop. Ask the clinician which terms apply to the actual examination or test result.

Involuntary movements

Involuntary contractions of muscle leading to involuntary movements of extremities, neck, trunk, or face.

Strabismus

A misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error.

Blindness

Blindness is the condition of lacking visual perception defined as a profound reduction in visual perception. On the 6m visual acuity scale, blindness is defined as less than 3/60. On the 20ft visual acuity scale, blindness is defined as less than 20/400. On the decimal visual acuity scale, blindness is defined as less than 0.05. Blindness is typically characterized by a visual field of no greater than 10 degrees in radius around central fixation.

Nystagmus

Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.

Which doctor should you see?

The suggested department for discussing Autosomal recessive congenital stationary night blindness is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Autosomal recessive congenital stationary night blindness. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.