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Smith-Mageni Syndrome


ICD-10: Q87.8
ORPHA: 819

Estimated occurrence

5:100 000 newborns


Lack of chromosome segment (deletion) on chromosome 17 or change (mutation) in the RAI1 gene (retinoic acid-induced gene 1).

General symptoms

Suckling difficulties and slow weight gain is common in infancy. Muscle weakness and low sensitivity to pain is often present, and most sufferers have a mild or moderate developmental disability. The children are short, but many still reach a normal final height. Many develop scoliosis at an early stage, and the arch of the foot can be flattened or too high. A wide gait is typical for the diagnosis. Sleep disturbances with short sleep cycles are a big problem. Self-harming behaviour, difficulties adapting and habitual actions can be present, as well as hyperactivity and sudden mood swings. Many of the body’s organs, such as the heart, kidneys, urinary tracts, thyroid gland, stomach and intestinal canal, eyes and ears can be affected. Epilepsy occurs.

Orofacial/odontological symptoms

Characteristic facial features are associated with the diagnosis. Reduced palate function (velopharyngeal insufficiency) is common, and can lead to difficulties sucking and swallowing and hyper-nasal speech. Many have a hoarse voice, caused by a divergence in the larynx, for example goose bumps on the vocal cords or vocal cord paralysis. Oral motor function impairments in the shape of muscle weakness and reduced mobility can affect speech and eating development and cause drooling. Some have biting habits. Dental buds may be missing, crown and/or root divergence can be prevalent, and some have divergent bites. Risk factors for oral health are difficulties working for oral/dental care, difficulties eating, as well as reduced own ability to clean the mouth after a meal due to oral motor limitations.

Orofacial/odontological treatment

  • It is important for people with this diagnosis to have contact with dental care early on for strengthened preventive care and oral health information.
  • Tooth and bite development is to be monitored. In case of divergence, an orthodontist is to be consulted at an early stage to plan any orthodontic treatment.
  • Contact with a physician when giving dental treatment to people with medical conditions such as heart defects is recommended.
  • Oral motor training and stimulation is often urgently needed in cases with eating difficulties, speech difficulties and drooling.
  • Speech, language and communication difficulties are evaluated and treated by a speech therapist.


  • The rare disease database of the Swedish National Board of Health and Welfare.
  • The MHC database - The Mun-H-Center database on oral health and orofacial function in rare diseases.
  • The Documentation from the Ågrenska national competence centre for rare diseases.
Updated: 2017-09-13 08:28