Duane-radial ray syndrome

Left Duane Type I

Duane-radial ray syndrome (DRRS) is a rare genetic disorder characterized by abnormalities in the development of the eyes and upper limbs. It is also known as Okihiro syndrome. The condition is named after Alexander Duane, who first described the eye movement disorder, and the radial ray anomalies that affect the bones in the arms and hands.

Clinical Features

Individuals with Duane-radial ray syndrome typically present with a combination of Duane syndrome and radial ray anomalies.

Duane Syndrome

Duane syndrome is a congenital eye movement disorder where there is limited horizontal eye movement. It is caused by the abnormal development of the sixth cranial nerve, which controls the lateral rectus muscle responsible for moving the eye outward. This can result in:

• Limited ability to move the eye outward (abduction)
• Limited ability to move the eye inward (adduction)
• Retraction of the eyeball into the socket when attempting to look inward

Radial Ray Anomalies

Radial ray anomalies refer to defects in the development of the radius bone in the forearm and the thumb. These anomalies can range from mild to severe and may include:

• Hypoplasia or aplasia of the radius
• Hypoplasia or aplasia of the thumb
• Triphalangeal thumb (thumb with three phalanges instead of two)
• Absent or underdeveloped bones in the forearm

Genetics

Duane-radial ray syndrome is typically inherited in an autosomal dominant pattern, meaning one copy of the altered gene in each cell is sufficient to cause the disorder. The condition is often associated with mutations in the SALL4 gene, which plays a crucial role in the development of multiple tissues and organs during embryogenesis.

Diagnosis

Diagnosis of Duane-radial ray syndrome is based on clinical evaluation, detailed patient history, and identification of characteristic physical findings. Genetic testing can confirm the diagnosis by identifying mutations in the SALL4 gene.

Management

Management of Duane-radial ray syndrome is symptomatic and supportive. Treatment may involve:

• Surgical correction of eye movement abnormalities
• Orthopedic interventions for limb anomalies
• Physical and occupational therapy to improve function and mobility

Related Conditions

Duane-radial ray syndrome shares features with other conditions, including:

• Holt-Oram syndrome
• Fanconi anemia
• VACTERL association

See Also

• Duane syndrome
• Radial ray anomaly
• SALL4
• Autosomal dominant inheritance

External Links

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