Duane-radial ray syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Duane-radial ray syndrome, also called Okihiro syndrome, is characterized by abnormalities of the bones in the arms and hands that may be associated with problems in the eyes, ears, and other organs. The particular features of the condition can vary greatly among affected individuals.

People with Duane-radial ray syndrome often have underdeveloped or absent thumbs, an extra thumb, or a long thumb that looks like a finger. Partial or complete absence of bones in the forearm is also common. Together, these hand and arm abnormalities are known as radial ray malformations.

People with Duane-radial ray syndrome may also have a disorder called Duane anomaly (also known as Duane retraction syndrome), which can affect one or both eyes. This condition occurs when certain nerves that control eye movement do not develop properly. Duane anomaly may limit outward eye movement (toward the ear) or inward eye movement (toward the nose). In people with this condition, the eyeball may pull back (retract) into its socket and the eyelid opening may narrow as the eye moves to the side. Because the eyes often do not look in the same direction (strabismus), affected individuals may need to turn their head to track objects with both eyes.

A variety of other signs and symptoms may be seen in people with Duane-radial ray syndrome. These can include hearing loss, unusually shaped ears, additional eye abnormalities, an inward- and upward-turning foot (clubfoot), fused spinal bones, a spine that curves to the side (scoliosis), and abnormalities of the anus and rectum (anorectal abnormalities). Affected individuals may also have heart and kidney defects.

Duane-radial ray syndrome is often considered to be part of a disease spectrum with other conditions that share similar features. Because these conditions are all caused by changes in the same gene, they are sometimes called SALL4-related disorders.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Genetic changes that cause disease are called pathogenic variants. Pathogenic variants in the SALL4 gene cause Duane-radial ray syndrome. The SALL4 gene plays a role in the proper formation of tissues and organs before birth. This gene provides instructions for making a protein that acts as a transcription factor, which means it binds to specific regions of DNA and helps control the activity of particular genes. Although the exact function of the SALL4 protein is unclear, it appears to be important for the normal development of the eyes, heart, and limbs.

Most of the pathogenic variants in the SALL4 gene that cause Duane-radial ray syndrome are considered “loss-of-function variants” because they reduce the activity of the SALL4 protein or decrease the amount of protein that is produced by cells. While a reduction in the amount of SALL4 protein seems to affect development before birth, it is unclear why the eyes, arms, and hands are particularly affected in people with Duane-radial ray syndrome.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

Duane-radial ray syndrome is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In many cases, an affected person inherits the pathogenic variant from a parent. Other cases result from a new (de novo) variant in the gene that occurs during the formation of reproductive cells (eggs or sperm) in an affected individual's parent or during early embryonic development. These individuals typically have no history of the disorder in their family.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Duane-radial ray syndrome is a rare condition, although its exact prevalence is unknown.

Which doctor should you see?

The suggested department for discussing Duane-radial ray syndrome 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 Duane-radial ray syndrome. 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.