Those with this condition can have affected parents, but it can also manifest for the first time with no family history which is called de novo. Since Duane-radial ray syndrome is an autosomal dominant disorder, there is a 50% chance of passing the mutation on to offspring. Mechanism
The mechanism for this disorder is somewhat unclear. What is known is that Duane-radial ray syndrome begins with mutations in the SALL4 gene. Due to these mutations, the proteins involved in embryonic development for making tissues and organs are not functioning properly. These proteins then cause improper development of bones (e.g. absence of the radius), abnormal eye movements, and other miscellaneous symptoms. Diagnosis
The diagnosis for this syndrome is based on clinical findings on a physical exam and the presence of a heterozygous SALL4 pathogenic variant. During the physical exam, Duane-radial ray syndrome is clinically established by the following clinical findings:

Duane Anomaly
Limitation of abduction of the eye
Retraction of the globe
Narrowing of the palpebral fissure during adduction
Radial Ray Malformations
Malformed, absent, or extra thumb
A thumb that looks more like a finger
Duplication of the thumb (preaxial polydactyly)
Deformity of the arm due to a lack of the radius
Any of the symptoms above that can observed
Hearing loss
Clubfoot
Unusually shaped ears

Related conditions
The varied signs and symptoms of Duane-radial ray syndrome often overlap with features of other disorders. For example, acro-renal-ocular syndrome is characterized by Duane anomaly and other eye abnormalities, radial ray malformations, and kidney defects. Both conditions can be caused by mutations in the same gene.
Duane-radial ray syndrome, also known as Okihiro Syndrome, is a rare autosomal dominant disorder that primarily affects the eyes (Duane anomaly) and causes abnormalities of bones in the arms and hands (radial ray malformations). This disorder is considered to be a SALL4-related disorder due to the SALL4 gene mutations leading to these abnormalities. It is diagnosed by clinical findings on a physical exam as well as genetic testing and imaging. After being diagnosed, there are other evaluations that one may go through in order to determine the extent of the disease. There are various treatments for the symptoms of this disorder. Symptoms
Duane-radial ray syndrome has two major features that appear in the majority of cases. These two features are Duane anomaly and radial ray malformations. Each feature appears in 65% and 91% of cases respectively. Duane Anomaly
Also known as Duane syndrome, Duane anomaly is a congenital strabismus syndrome that is characterized by certain eye movements. This results from improper nerve development for eye movement.The following are characteristics of Duane anomaly:
Inability to fully abduct (away from the midline) the eye either unilaterally or bilaterally
Narrowing of the palpebral fissure
Retraction of the globe on adduction (toward the midline)
Absence of the abducens nucleus and nerve (cranial nerve VI)
Abnormal eye movement due to the lateral rectus muscle being innervated by a branch of the oculomotor nerve (cranial nerve III)

Radial Ray Malformations
This is characterized by hand and arm abnormalities.