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Smith-Magen syndrome (SMS). What we need to know

Smith-Magen syndrome is a chromosomal disorder, a complex developmental disorder that affects multiple organ systems in the body. The disorder is characterized by a number of anomalies present at birth (congenital), as well as behavioral and cognitive problems.

A small part of chromosome 17 is deleted in each cell of a person with Smith-Magen syndrome. The deleted segment most often includes a DNA building block of about 3,7 million, also called 3,7 megabases (Mb). Although the deleted portion contains several genes, researchers believe that the loss of one particular gene, RAI1, underlies many of the features of Smith-Magen syndrome. The RAI1 gene provides instructions for making a protein that helps activate other genes. It is not clear how the loss of one copy of the RAI1 gene causes other physical, mental or behavioral problems associated with the disease.

Synonyms of disease

  • 17p- syndrome;
  • 17p11.2 monosomy;
  • deletion of chromosome 17p;
  • partial monosomy 17p;
  • SMS.


Smith-Magen syndrome is usually not inherited. This is usually caused by a genetic change that occurs during the production of reproductive cells (eggs or sperm) or during early fetal development. Since this is a genetic disorder, the child is born with this syndrome.


Signs and symptoms of Smith-Magen include:

  • sleep disorders (insomnia);
  • wide and square face;
  • eyes close together, with a deep slit;
  • wide cheeks and prominent jaw;
  • full lips and wide mouth;
  • Anomalies of the larynx;
  • anxiety and impulsivity;
  • overweight in adolescence;
  • low height;
  • velopharyngeal insufficiency;
  • curvature of the spine (scoliosis);
  • Decreased sensitivity to pain and temperature;
  • Heart and kidney defects are less common;
  • Visual defects.

sleep disorders

Sleep problems are very common in people with MS (75-100%). With age, people with SMS syndrome begin to experience sleep disturbances, which means less sleep at night and more sleep during the day. Daytime sleepiness refers to "sleep attacks," indicating the sudden and overwhelming nature of the urge to sleep. Daytime sleepiness can cause various social problems and mental disorders.

A possible cause of sleep disturbances is the inverse release of the hormone melatonin, which disrupts the circadian rhythm (the rhythm that tells our body when it is day and night according to sleep patterns). However, not all people with MS who experience sleep disturbances may have melatonin secretion disorders, suggesting that this is not the only cause of sleep difficulties; It is likely that the environment and lifestyle also have a significant impact on the sleep of people with MS.


The diagnostics of Smith-Magen syndrome is based on the identification of characteristic symptoms, a detailed description of the patient's and family's history, a thorough clinical examination and various specialized genetic tests. The diagnostics of SMS is confirmed by detection of 17p11.2 deletion (cytogenetic analysis or microarray) or RAI1 gene mutation.

There are two main types of tests available to prevent fetal syndromes during pregnancy (prenatal period): screening tests and diagnostic tests. Screening and diagnostic tests determine whether a fetus has a low or high chance of developing various syndromes.

If screening tests show that you have a high risk of having a baby with Smith-Magene, it is recommended that you also have a diagnostic test to determine if the fetus has the genetic disorder.

1. Screening Tests – A prenatal screening test can determine if your baby is more or less likely to have birth defects, many of which are genetic disorders. These tests include blood tests, specific ultrasounds, and prenatal cell-free DNA screening.

2. Diagnostic tests – after the screening test, the final answer is given by the diagnostic test, which checks the genetic material of the fetus and therefore can also find out whether the fetus has a genetic disorder. Invasive and non-invasive prenatal diagnostic tests ((NIPT) Verasity, Veragen) are the only, safe and effective way to confirm the diagnostics. Be aware that some diagnostic tests, such as chorionic villus sampling and amniocentesis, carry a small risk of miscarriage.

Learn more about prenatal diagnostics → (


Treatment may require the coordinated efforts of a team of medical specialists, such as pediatricians, surgeons, cardiologists, dentists, speech therapists, ophthalmologists, psychologists, and other health care professionals, to help relieve symptoms early on.

Psychosocial support from family members and friends is also necessary. Children with MS often need several forms of help, including physical therapy, behavioral therapy, occupational therapy, and speech therapy. After visiting the doctor, the patient may be prescribed medication.


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