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Smith-Magenis syndrome


Other Names for this Disease

  • Chromosome 17p11.2 deletion syndrome
  • SMS
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Symptoms

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What are the signs and symptoms of Smith-Magenis syndrome?

The major features of Smith-Magenis syndrome include mild to moderate intellectual disability, delayed speech and language skills, distinctive facial features, sleep disturbances, and behavioral problems.[1]

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.[1]

Disrupted sleep patterns are characteristic of Smith-Magenis syndrome, typically beginning early in life. Affected people may be very sleepy during the day, but have trouble falling asleep and awaken several times each night.[1]

People with Smith-Magenis syndrome 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. Repetitive self-hugging is a behavioral trait that may be unique to Smith-Magenis syndrome. People with this condition also compulsively lick their fingers and flip pages of books and magazines (a behavior known as 'lick and flip').[1]

Other signs and symptoms of Smith-Magenis syndrome include short stature, abnormal curvature of the spine (scoliosis), reduced sensitivity to pain and temperature, 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.[1]

Last updated: 8/22/2014

The Human Phenotype Ontology provides the following list of signs and symptoms for Smith-Magenis syndrome. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms.

Signs and Symptoms Approximate number of patients (when available)
Attention deficit hyperactivity disorder 90%
Brachydactyly syndrome 90%
Broad forehead 90%
Cognitive impairment 90%
Deeply set eye 90%
Depressed nasal bridge 90%
Frontal bossing 90%
Malar flattening 90%
Neurological speech impairment 90%
Obesity 90%
Reduced number of teeth 90%
Sleep disturbance 90%
Stereotypic behavior 90%
Synophrys 90%
Taurodontia 90%
Tented upper lip vermilion 90%
Upslanted palpebral fissure 90%
Abnormality of the larynx 75%
Brachycephaly 75%
Broad face 75%
Broad palm 75%
Delayed speech and language development 75%
Everted upper lip vermilion 75%
Generalized hypotonia 75%
Hoarse voice 75%
Hyporeflexia 75%
Mandibular prognathia 75%
Morphological abnormality of the middle ear 75%
Self-mutilation 75%
Short palm 75%
Abnormal form of the vertebral bodies 50%
Abnormality of the outer ear 50%
Abnormality of the tongue 50%
Abnormality of the tracheobronchial system 50%
Anteverted nares 50%
Aplasia/Hypoplasia of the corpus callosum 50%
Clinodactyly of the 5th finger 50%
Conductive hearing impairment 50%
Constipation 50%
EEG abnormality 50%
Gait disturbance 50%
Hyperacusis 50%
Hypercholesterolemia 50%
Hypertelorism 50%
Hypertriglyceridemia 50%
Impaired pain sensation 50%
Malformation of the heart and great vessels 50%
Microcornea 50%
Micrognathia 50%
Myopia 50%
Open mouth 50%
Otitis media 50%
Pes planus 50%
Prenatal movement abnormality 50%
Scoliosis 50%
Short nose 50%
Short philtrum 50%
Short stature 50%
Strabismus 50%
Toe syndactyly 50%
Velopharyngeal insufficiency 50%
Ventriculomegaly 50%
Wide nasal bridge 50%
Abnormality of the immune system 33%
Seizures 33%
Abnormal localization of kidney 7.5%
Abnormality of the forearm 7.5%
Abnormality of the genital system 7.5%
Abnormality of the ureter 7.5%
Cleft palate 7.5%
Cleft upper lip 7.5%
Hand polydactyly 7.5%
Hypothyroidism 7.5%
Limitation of joint mobility 7.5%
Precocious puberty 7.5%
Renal hypoplasia/aplasia 7.5%
Retinal detachment 7.5%
Abnormal renal morphology -
Areflexia -
Autosomal dominant inheritance -
Head-banging -
Intellectual disability -
Midface retrusion -
Sporadic -

Last updated: 12/1/2014

The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature.

The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined.

Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.


References
  1. Smith-Magenis syndrome. Genetics Home Reference (GHR). December 2013; http://ghr.nlm.nih.gov/condition=smithmagenissyndrome. Accessed 8/22/2014.


Other Names for this Disease
  • Chromosome 17p11.2 deletion syndrome
  • SMS
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.