Andermann syndrome

Individuals with Andermann syndrome have abnormal or absent reflexes and weak muscle tone. They may experience muscle wasting with progressive weakness, loss of feeling in their arms and legs, and have rhythmic shaking (tremors). Individuals learn to walk, often late, between ages 3 and 4, but lose this ability by adolescence. If the cranial nerves are impacted, the facial muscles may be weak. Eyelids may droop (ptosis) and eyes may not track objects well. Joint contractures occur as affected individuals get older. Many develop curvature of the spine (scoliosis), which may require surgery to correct.

Other physical features may include widely spaced eyes (hypertelorism); a short skull (brachycephaly); a higher than normal hard palate in the mouth; a big toe that crosses over the other toes; and partially fused second and third toes (syndactyly).

Individuals usually have intellectual disabilities, which range from mild to severe. Some experience seizures.