Smith-Magenis syndrome

Smith-Magenis syndrome is a developmental disorder that affects behavior, emotions, and learning processes. The major features of this condition include distinctive facial features, sleep disturbances, behavioral problems, mild to moderate intellectual disability, and delayed speech and language skills.

Most people with Smith-Magenis syndrome have a broad, square-shaped face with deep-set eyes, full cheeks, and a prominent lower jaw. The middle of the face and the bridge of the nose often appear flattened. The mouth tends to turn downward with a full, outward-curving upper lip. These facial differences can be subtle in early childhood, but they usually become more distinctive in later childhood and adulthood. Dental abnormalities are also common in affected individuals.

Disrupted sleep patterns are characteristic of Smith-Magenis syndrome, and they typically begin early in life. Affected people may have trouble falling asleep at night and awaken several times during the night and early morning. They may be very sleepy during the day.

People with Smith-Magenis syndrome typically have affectionate, engaging personalities, but most also have behavioral problems. These include frequent temper tantrums and outbursts, aggression, anxiety, impulsiveness, and difficulty paying attention. Self-injury, including biting, hitting, head banging, and skin picking, is very common. People with Smith-Magenis syndrome may have other behaviors, such as repetitive self-hugging or compulsively licking their fingers and flipping pages of books and magazines (a behavior known as "lick and flip").

Other signs and symptoms of Smith-Magenis syndrome include short stature, abnormal curvature of the spine (scoliosis), obesity, and a hoarse voice. Some people with this disorder have ear abnormalities that lead to hearing loss. Affected individuals may have eye abnormalities that cause nearsightedness (myopia) and other vision problems. Although less common, heart and kidney defects also have been reported in people with Smith-Magenis syndrome.