Smith-Magenis syndrome
Last updated 4 May 2023
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Smith-Magenis syndrome is a developmental disorder that affects behaviour, emotions, and learning processes. The major features of this condition include distinctive facial features, sleep disturbances, behavioural problems, mild to moderate intellectual disability, and delayed speech and language skills.
Description
Smith-Magenis syndrome is a developmental disorder that affects behaviour, emotions, and learning processes. The major features of this condition include distinctive facial features, sleep disturbances, behavioural problems, mild to moderate intellectual disability, and delayed speech and language skills.
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.
Disrupted sleep patterns are characteristic of Smith-Magenis syndrome, and they typically begin early in life. Affected people may have trouble falling asleep at night and awaken several times during the night and early morning. They may be very sleepy during the day.
People with Smith-Magenis syndrome typically have affectionate, engaging personalities, but most also have behavioural 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. People with Smith-Magenis syndrome may have other behaviors, such as repetitive self-hugging or compulsively licking their fingers and flipping pages of books and magazines (a behaviour known as "lick and flip").
Other signs and symptoms of Smith-Magenis syndrome include short stature, abnormal curvature of the spine (scoliosis), obesity, 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.
Inheritance patterns
The source lists the following possible inheritance patterns: Not inherited. More than one pattern can apply in different cases.
Related genes
Other names
17p- syndrome
17p11.2 monosomy
Chromosome 17p deletion syndrome
Deletion 17p syndrome
Partial monosomy 17p
SMS
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Further reading and references
- Smith-Magenis syndrome; MedlinePlus, National Library of Medicine.
- Carmona-Mora P, Encina CA, Canales CP, Cao L, Molina J, Kairath P, Young JI, Walz K. Functional and cellular characterization of human Retinoic Acid Induced 1 (RAI1) mutations associated with Smith-Magenis Syndrome. BMC Mol Biol. 2010 Aug 25;11:63. doi: 10.1186/1471-2199-11-63.
- De Leersnyder H. Smith-Magenis syndrome. Handb Clin Neurol. 2013;111:295-6. doi: 10.1016/B978-0-444-52891-9.00034-8.
- Elsea SH, Williams SR. Smith-Magenis syndrome: haploinsufficiency of RAI1 results in altered gene regulation in neurological and metabolic pathways. Expert Rev Mol Med. 2011 Apr 19;13:e14. doi: 10.1017/S1462399411001827.
- Girirajan S, Elsas LJ 2nd, Devriendt K, Elsea SH. RAI1 variations in Smith-Magenis syndrome patients without 17p11.2 deletions. J Med Genet. 2005 Nov;42(11):820-8. doi: 10.1136/jmg.2005.031211. Epub 2005 Mar 23.
- Girirajan S, Vlangos CN, Szomju BB, Edelman E, Trevors CD, Dupuis L, Nezarati M, Bunyan DJ, Elsea SH. Genotype-phenotype correlation in Smith-Magenis syndrome: evidence that multiple genes in 17p11.2 contribute to the clinical spectrum. Genet Med. 2006 Jul;8(7):417-27. doi: 10.1097/01.gim.0000228215.32110.89.
- Madduri N, Peters SU, Voigt RG, Llorente AM, Lupski JR, Potocki L. Cognitive and adaptive behavior profiles in Smith-Magenis syndrome. J Dev Behav Pediatr. 2006 Jun;27(3):188-92. doi: 10.1097/00004703-200606000-00002.
- Neira-Fresneda J, Potocki L. Neurodevelopmental Disorders Associated with Abnormal Gene Dosage: Smith-Magenis and Potocki-Lupski Syndromes. J Pediatr Genet. 2015 Sep;4(3):159-67. doi: 10.1055/s-0035-1564443. Epub 2015 Sep 28.
- Potocki L, Glaze D, Tan DX, Park SS, Kashork CD, Shaffer LG, Reiter RJ, Lupski JR. Circadian rhythm abnormalities of melatonin in Smith-Magenis syndrome. J Med Genet. 2000 Jun;37(6):428-33. doi: 10.1136/jmg.37.6.428.
- Smith AC, Dykens E, Greenberg F. Behavioral phenotype of Smith-Magenis syndrome (del 17p11.2). Am J Med Genet. 1998 Mar 28;81(2):179-85. doi: 10.1002/(sici)1096-8628(19980328)81:23.0.co;2-e.
- Smith ACM, Berens J, Boyd KE, Brennan C, Gropman A, Haas-Givler B, Vlangos C, Foster R, Franciskovich R, Girirajan S, Raitano Lee N, Taylor C, Turnacioglu SO, Elsea SH. Smith-Magenis Syndrome. 2001 Oct 22 [updated 2026 Apr 2]. In: Adam MP, Bick S, Mirzaa GM, Wallace SE, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2026. Available from http://www.ncbi.nlm.nih.gov/books/NBK1310/
- Tomona N, Smith AC, Guadagnini JP, Hart TC. Craniofacial and dental phenotype of Smith-Magenis syndrome. Am J Med Genet A. 2006 Dec 1;140(23):2556-61. doi: 10.1002/ajmg.a.31371.
- Zori RT, Lupski JR, Heju Z, Greenberg F, Killian JM, Gray BA, Driscoll DJ, Patel PI, Zackowski JL. Clinical, cytogenetic, and molecular evidence for an infant with Smith-Magenis syndrome born from a mother having a mosaic 17p11.2p12 deletion. Am J Med Genet. 1993 Sep 15;47(4):504-11. doi: 10.1002/ajmg.1320470414.
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