SMS FACTS

Other signs and symptoms of Smith-Magenis syndrome include short stature, abnormal curvature of the spine (scoliosis), reduced sensitivity to pain and temperature and also 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 problems with vision. Heart and kidney defects also have been reported in people with Smith-Magenis syndrome, though they are less common.

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.

Our bodies produce Melatonin at night to tell us we are tired. People with the microdeletion produce this hormone in the afternoon; our noon hour can be their midnight. This is why behaviors can be escalated during the day when poor sleep is had the night before. It’s also why people with Smith Magenis Syndrome will nap at odd times throughout their life.

Although SMS is caused by a deletion of genetic material, it usually does not run in families. In most cases, the deletion occurs accidentally in a child around the time he or she is conceived, without being inherited from either parent. For this reason, we can say that SMS is clearly genetic, but not usually familial. The risk to siblings depends on the results of parental chromosome analysis. If parental chromosomes are normal, the risks to subsequent pregnancies are extremely low. Families are advised to consult a genetics counselor or specialist for further advice regarding their own particular family situation.

Although the exact incidence is not known, it is estimated that SMS occurs in 1 out of 25,000 births, however the actual prevalence may be closer to 1 in 15,000 births. SMS is vastly under-diagnosed. Recent data indicates that there are approximately 600 known cases world-wide. But as awareness of it increases, the number of people identified grows every year.

Smith-Magenis syndrome (or SMS) is a chromosomal disorder characterized by a recognizable pattern of physical, behavioral, and developmental features. It is caused by a missing piece of genetic material from chromosome 17, referred to as deletion 17p11.2.

Common features include: characteristic, yet subtle, facial appearance, infant feeding problems, low muscle tone, developmental delay, variable levels of intellectual disability, early speech/language delay, middle ear problems, skeletal anomalies and decreased sensitivity to pain. The syndrome also includes a distinct pattern of neurobehavioral features characterized by chronic sleep disturbances, arm hugging/hand squeezing, hyperactivity and attention problems, prolonged tantrums, sudden mood changes and/or explosive outbursts and self-injurious behaviors.