Overview
NYX encodes nyctalopin, a leucine-rich proteoglycan important for signal transmission between photoreceptors and bipolar cells in the retina. Mutations in NYX lead to congenital stationary night blindness type 1 (CSNB1), an X-linked eye disease that mainly affects males.
Xp11.4 (X chromosome)
Hereditary Diseases
X-linked recessive
Rare, affects mainly males
Function & Significance
Nyctalopin is a membrane protein localized at the synapse between photoreceptors (rods) and ON-bipolar cells. It is essential for correct signal transmission in the retina, particularly for dark adaptation.
In mutations in NYX, synaptic transmission is disrupted, leading to night blindness. Day vision is typically normal or only slightly impaired. The disease is “stationary,” meaning it does not worsen over time.
🔬 Congenital Stationary Night Blindness (CSNB)
CSNB is a group of eye disorders characterized by night blindness from birth. There are two main types: CSNB1 (with abnormal ERG) and CSNB2 (with normal ERG). NYX mutations cause CSNB1. Other genes that cause CSNB include TRPM1, GRM6, CACNA1F, and CABP4.
Associated Diseases
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🌙 Congenital Stationary Night Blindness Type 1 (CSNB1)
Night blindness from birth, normal or slightly reduced day vision, myopia, nystagmus
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👁️ X-linked Night Blindness
Affects mainly males; females are carriers and usually asymptomatic
🧬 Relevant SNPs
Over 50 different mutations in NYX have been described. Most are private mutations (found only in individual families). Common mutation types include missense, nonsense, frameshift, and splice-site mutations. There is no single common mutation.
⚕️ Clinical Significance
Diagnosis: Electroretinogram (ERG) shows characteristic changes with a missing b-wave. Clinical examination reveals night blindness, often with myopia and nystagmus. Genetic tests confirm NYX mutations.
Management: No causal therapy available. Symptomatic treatment:
- Glasses/Contact Lenses: For myopia correction
- Lighting: Bright lighting at night, avoidance of darkness
- Fitness to Drive: Night driving ban in many countries
Prognose: Stationary, no worsening over time. Normal life expectancy. Day vision is usually sufficient for normal activities.
Genetic Counseling: X-linked inheritance means that daughters of affected men are carriers, sons are not affected. Carriers have a 50% risk of having affected sons.
📚 Data Sources
The information on this page is based on the following scientific sources:
- OMIM: #300278 (Night Blindness, Congenital Stationary, Type 1A)
- ClinVar: Pathogenic NYX variants
- PubMed: Literature on congenital stationary night blindness
- Orphanet: ORPHA99827 (X-linked congenital stationary night blindness)
Last Update: February 2026