What is Smith-Magenis Syndrome?

Smith-Magenis syndrome is an uncommon genetic disorder that can cause a number of different physical defects and mental health problems. The condition results from a random deletion of a particular gene on chromosome 17 during early fetal development. People with Smith-Magenis syndrome are typically shorter than average and have broad, pronounced facial features. Most sufferers also have some degree of mental retardation and are prone to aggressive behavioral problems. With dedicated treatment and support, many patients are able to function somewhat independently in society and reach normal life expectancy.

Decades of genetic research have pinpointed the cause of Smith-Magenis syndrome. A protein-encoding gene called RAI1 is partially or totally absent on chromosome 17 of affected individuals. While the exact function of RAI1 is not completely understood, it is clear that it contributes to both physical and mental development. The condition is rarely inherited; new cases tend to appear spontaneously without any family history of Smith-Magenis syndrome or other related genetic disorders.

Infants who are born with Smith-Magenis syndrome may not immediately exhibit symptoms. In most cases, a diagnosis is not made until early childhood. Most children with the disorder have characteristic facial features such as broad cheeks, a pronounced lower jaw, a protruding upper lip, and a flat nose. In addition, they may be shorter than their peers, have poor muscle tone, and show early signs of scoliosis. A majority of children have developmental problems that impair their ability to learn how to speak, read, and get along with others.

Sleeping problems are common with Smith-Magenis syndrome as well. Children and adults often have trouble falling asleep at night and staying asleep until morning, and during the day, they may be excessively tired and lethargic. Behavioral outbursts, such as throwing temper tantrums, hitting themselves or others, and screaming are common as well. Sufferers also tend to lose interest in activities quickly and become highly impatient.

Modern advancements in genetic testing allow specialists to identify missing RAI1 genes in blood samples. Some cases are misdiagnosed, however, which can lead to delayed or improper treatment. In general, it is important to get more than one professional opinion from doctors whenever a child appears to show symptoms of Smith-Magenis syndrome.

There is no cure for the disorder, but steps can be taken to improve a patient's symptoms and quality of life. Medications are often prescribed to improve concentration, attention span, and sleeping difficulties. Spine surgery may be necessary if scoliosis causes pain and a limited range of motion. In addition to medical care, many young patients require constant family support with eating, bathing, dressing, and using the bathroom. Ongoing physical therapy and speech training can help patients gain independence and confidence.