What are the genetic changes related to Moebius syndrome ?
The causes of Moebius syndrome are unknown, although the condition probably results from a combination of environmental and genetic factors. Researchers are working to identify and describe specific genes related to this condition. The disorder appears to be associated with changes in particular regions of chromosomes 3, 10, or 13 in some families. Certain medications taken during pregnancy and abuse of drugs such as cocaine may also be risk factors for Moebius syndrome.  Many of the signs and symptoms of Moebius syndrome result from the absence or underdevelopment of cranial nerves VI and VII. These nerves, which emerge from the brainstem at the back of the brain, control back-and-forth eye movement and facial expressions. The disorder can also affect other cranial nerves that are important for speech, chewing, and swallowing. Abnormal development of cranial nerves leads to the facial muscle weakness or paralysis that is characteristic of Moebius syndrome.  Researchers speculate that Moebius syndrome may result from changes in blood flow to the brainstem during early stages of embryonic development. However, it is unclear what causes these changes to occur and why they specifically disrupt the development of cranial nerves VI and VII. Even less is known about the causes of some other signs and symptoms of this condition, including hand and foot abnormalities.