This syndrome involves paralysis of certain facial nerves. The features of this syndrome are mainly related to the nerve paralysis.
Which nerves are involved?
In Moebius syndrome the 6th and 7th cranial nerves do not fully develop. This can lead to paralysis of the underdeveloped nerves. The paralysis can be unilateral (one side of the face) or bilateral (both sides of the face). Other cranial nerves that are also sometimes involved are 3, 4, 5, 9, 10 and 12. The table below shows some of the functions of the nerves that can involved in Moebius syndrome.
The table below shows some of the functions of cranial nerves that can be involved in Moebius syndrome:
|6||Side-to side eye movement|
|7||Facial expressions, taste, blinking|
|3||Eye lid and eyeball movement|
|5||Chewing, facial sensations|
|9||Taste, helps with swallowing|
|10||Conveys sensory and motor information to and from several organs in the chest and abdomen|
What does the paralysis of these nerves mean for the person with Moebius syndrome?
Parents may notice their baby with Moebius syndrome does not suck as strongly and drools more than a baby that does not have Moebius syndrome. A person with Moebius syndrome will probably not be able to move their eyes from side to side, but they will be able to move them up and down. The blinking action may also be difficult. These symptoms can usually be seen in a baby. As children start to learn to speak, they may have some difficulties making sounds that involve using the lips and tongue, and making facial expressions, such as smiling.
Can a person with Moebius syndrome have other problems?
There can be skeletal involvement in Moebius syndrome. This may include clubfoot, missing or webbed fingers. Webbed fingers occur when there is skin either completely or partial joining two or more fingers together. If a child is born with a clubfoot it can sometimes be corrected without surgery. A series of casts are put on the foot to straighten it. Children with Moebius syndrome are more likely to have low (or poor) muscle tone, particularly of the upper body. This can lead to the children learning to do things like sit, crawl and walk later than other children. It is not known why some children have these other problems. 85% of children with Moebius syndrome do not have learning problems.
Can Moebius syndrome occur more than once in a family?
All most all cases of Moebius syndrome are sporadic. This means they occur once in a family, with a low chance of it occurring in another pregnancy. The recurrence risk (chance of another child having Moebius syndrome) is around 2%, so there is a 98 % chance that it will not happen again. There are some rare families where more than one person is affected. In the rare families where multiple people have Moebius syndrome, the syndrome can be inherited in one of three ways: autosomal dominant, autosomal recessive or sex linked.
Currently there is no diagnostic test for Moebius Syndrome. The diagnosis is made by clinical examination.
- Jones K.L., Smith’s Recognizable Patterns of Human Malformation. 5th Edition. W.B. Soliders Company A Division of Harcourt Brace and Company, 1997.
- Online Mendelian Inheritance in Man, OMIM (TM). McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University (Baltimore, MD) and National Center for Biotechnology Information, National Library of Medicine (Bethesda, MD), 2000.