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X-linked infantile nystagmus
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

X-linked infantile nystagmus

X-linked infantile nystagmus is a genetic condition characterized by involuntary, repetitive eye movements that typically begin at birth or within the first six months of life.

Overview

X-linked infantile nystagmus is a condition characterized by abnormal eye movements. Nystagmus refers to involuntary side-to-side, up-and-down, or circular movements of the eyes. In individuals with this condition, the movements are typically side-to-side and are present at birth or develop within the first six months of life.

The abnormal eye movements may worsen when an affected person feels anxious or attempts to stare directly at an object. Some individuals experience involuntary changes in the direction of their eye movements, known as periodic alternating nystagmus. The severity of the condition varies, even among affected individuals within the same family. To compensate for these irregular movements, some people may turn or tilt their head. Additionally, affected individuals may have other eye abnormalities, such as foveal hypoplasia, where the region at the back of the eye responsible for sharp central vision is underdeveloped.

Frequency

The incidence of X-linked infantile nystagmus is estimated to be 4.4 in 10,000 individuals.

Causes

Variants (mutations) in the FRMD7 gene cause X-linked infantile nystagmus. The FRMD7 gene provides instructions for making a protein found mostly in areas of the brain that control eye movement and in the light-sensitive tissue at the back of the eye (the retina). Research suggests that FRMD7 variants disrupt the development of certain nerve cells in the brain and retina.

In some cases, no variant in the FRMD7 gene is found, suggesting that variants in at least one other unidentified gene may cause the disorder. Nystagmus can also occur in people with other X-linked eye conditions, such as X-linked ocular albinism, which are caused by changes in genes associated with those specific conditions.

Gene Associated with X-linked Infantile Nystagmus

  • FRMD7

Inheritance

This condition is inherited in an X-linked pattern. The gene associated with this condition is located on the X chromosome. In males, who have one X chromosome, a variant in the only copy of the gene is sufficient to cause the condition. In females, who have two copies of the X chromosome, one altered copy can cause the condition, though features may be less severe than in individuals with two altered copies. Approximately half of females with only one altered copy of the FRMD7 gene have no symptoms.

Other Names for This Condition

  • Congenital motor nystagmus
  • FRMD7-related infantile nystagmus
  • Idiopathic infantile nystagmus
  • NYS1
  • X-linked congenital nystagmus
  • X-linked idiopathic infantile nystagmus

Frequently Asked Questions

No, X-linked infantile nystagmus does not cause complete blindness, nor is it a progressive degenerative disorder that worsens continuously over time. Affected individuals typically have mild to moderate reduction in visual acuity, often ranging from 20/40 to 20/100, though this varies depending on the presence and degree of foveal hypoplasia. Visual stability is usually maintained throughout life, and children learn to adapt using compensatory visual strategies.
Children frequently develop an abnormal head posture, such as a head turn, chin tilt, or head tilt, to position their eyes at their specific null point. The null point is the particular angle of gaze where the involuntary eye oscillations are slowest or minimal. By keeping their head in this position, the child stabilizes the retinal image and achieves their clearest possible vision.
The condition follows an X-linked pattern of inheritance and is primarily caused by variants in the FRMD7 gene on the X chromosome. Males have one X chromosome, so a single altered copy causes the condition. Females have two X chromosomes; while they are often unaffected carriers, random X-chromosome inactivation (lyonization) means that some carrier females can exhibit mild nystagmus or reduced visual acuity. An affected father will pass the gene variant to all of his daughters but none of his sons.
While there is no cure to eliminate nystagmus entirely, management focuses on maximizing visual function. Corrective eyeglasses or contact lenses treat associated refractive errors; contact lenses often provide superior stability because they move with the eye. Prism lenses can be prescribed to redirect the visual field so that the null point corresponds with straight-ahead viewing. In select cases, eye muscle surgery (strabismus or tenotomy surgery) is performed to mechanically shift the null point into primary gaze, significantly reducing neck strain and head tilting.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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