Moebius syndrome ... (Moebius syndrome)
Moebius syndrome is a congenital neurological condition that primarily affects the muscles that control facial expression and eye movement. Weakness or paralysis of the facial muscles is one of the most common features of Moebius syndrome. Affected individuals lack facial expressions, so you can not smile, frown or raise their eyebrows. Muscle weakness also causes feeding problems that manifest in early childhood.
Many people with Moebius syndrome are born with micrognatia and microstomia with a short tongue and unusual shape and cleft palate. These abnormalities contribute to speech problems that occur in many children with Moebius Syndrome. They are also common dental anomalies, including the absence of teeth or misaligned teeth. Moebius syndrome also affects muscles that control eye movement back and forth. Affected persons must move your head from side to side to read or follow the movement of objects. In addition, these individuals have difficulty maintaining eye contact, and strabismus. Moreover, the lids can not be closed completely, which may cause eye dryness and irritation.
Other features of Moebius syndrome may include abnormalities in the bones of the hands and feet, hypotonia, hearing loss and delayed development of motor skills. Some studies have suggested that children with Moebius Syndrome are more likely than unaffected children have autism spectrum characteristics, although recent studies have questioned this association. Because people have difficulty Moebius syndrome with eye contact and voice because of their physical differences, autism spectrum disorders may be difficult to diagnose in these individuals. Moebius syndrome may also be associated with a slightly increased risk of intellectual disability; however, most affected individuals have normal intelligence.
The causes of Moebius syndrome is unknown, although the disease is probably due to a combination of environmental and genetic factors. It is working to identify and describe the specific genes related to this process. Specifically, it appears to be associated with specific changes in the regions of chromosomes 3, 10, or 13 in some families. Certain drugs taken during pregnancy and drug abuse such as cocaine, may also be risk factors of Moebius syndrome.
Many of the signs and symptoms of Moebius syndrome are due to the absence or lack of development of cranial nerves VI and VII. These nerves that emerge from the brainstem at the back of the brain, controlling eye movement and facial expressions. The syndrome can also affect other cranial nerves that are important for speech, chewing and swallowing. Abnormal development of the cranial nerves leads to muscle weakness or facial paralysis that is characteristic of Moebius syndrome. Some researchers speculate that Moebius syndrome may be due to changes in blood flow to the brain stem during the early stages of embryonic development. However, it is unclear what causes these changes and why specifically disrupt the development of cranial nerves VI and VII.
Most cases of Moebius Syndrome are sporadic, meaning that occur in people with no history of disease in your family. A small percentage of all cases described in families; However, the syndrome has no clear pattern of inheritance.