Abstract

We report a mother and son with 5th, 6th, 7th, and bulbar cranial nerve paralysis, who had two similarly affected relatives. None of them had primary skeletal defects. Twenty-six previous reports of familial cases within the heterogeneous 'Möbius spectrum of defects' were reviewed. When cranial nerve palsies were associated with a primary skeletal defect, familial transmission was not found. No recurrence was noted in 31 cases with cranial nerve palsies associated with oral abnormalities and limb defects. The term Möbius syndrome should be restricted to cases with congenital 6th and 7th nerve paralysis with skeletal defects, who have a low recurrence risk (2%). The features in an index case which may indicate a higher risk of recurrence are the absence of skeletal defects, isolated facial palsy, deafness, ophthalmoplegia, and digital contractures. A recurrence risk of 25 to 30% in these cases appears reasonable.