Familial aplasia of the inferior rectus muscles.

PURPOSE: We describe inferior rectus aplasia in three members of a family. No family member showed signs of craniofacial dysostosis syndromes or neurofibromatosis. PATIENTS AND
FINDINGS: A woman with abnormal head posture, right exotropia, and right hypotropia presented to our clinic. She mentioned that her two children had similar problems. A provisional diagnosis of ocular fibrosis or atypical Duane syndrome was made and she underwent surgery. During surgery, the inferior rectus muscle could not be identified in either eye. Subsequently, her children were examined and orbital magnetic resonance imaging (MRI) was performed for all family members. MRI confirmed bilateral absence of the inferior rectus muscles in the mother and unilateral absence with atrophic and fibrotic contralateral inferior rectus muscles in the children.
CONCLUSION: This is the first report in the literature of a family with aplastic inferior rectus muscles with no signs of craniosynostosis or neurofibromatosis.