Paul Julius Moebius, a German neurologist, in 1888 described the first group of cases but even today its nature and description is controversial. A large number of non-ocular abnormalities have been reported to be associated with this syndrome but as yet its etiology remains unknown.
The two major features that are required to make the diagnosis are weakness of the facial muscles and inability to move the eyes to the side. The weakness of the facial muscles results in a fixed facial expression resembling a motionless mask. The eyes are unable to move to the side giving the appearance of being cross-eyed. No other consistent eye abnormalities have been found.
Without more knowledge regarding the cause of this presumed syndrome (some doubt its existence), the reported limb and neurological abnormalities may or may not be valid associations. These generally consist of malformations of the limbs and other neurological symptoms. Difficulties in motor coordination and balance are common and a few have more general learning difficulties.
The inheritance pattern, if any, is uncertain. The majority of cases are sporadic without having a history of the syndrome in other family members. No gene mutation has been found. Both autosomal dominant and autosomal recessive inheritance patterns have been reported in several families. One family with affected individuals in 3 generations had a consistent structural change in chromosome 13 suggesting that a causative gene may be located there.
The major risk to life occurs in infants and young children who may have breathing difficulties. Adults often have a full life depending on what other malformations they may or may not have. No treatment is available.