Knowra Smith–Magenis syndrome Smith–Magenis syndrome Smith–Magenis syndrome is a neurodevelopmental disorder usually caused by deletion of chromosome 17p11.2 or a pathogenic RAI1 variant. It is associated with developmental differences, distinctive behavioral features, and disrupted sleep.
RAI1 : RAI1 is a gene on chromosome 17 that encodes a transcriptional regulator involved in development and gene expression. Pathogenic variants in this gene can cause Smith–Magenis syndrome without a chromosome deletion.
Sleep disturbance : Sleep disturbance is difficulty with sleep timing, continuity, duration, or quality. Frequent night waking and early waking are prominent concerns in the syndrome.
Ann C. Smith : Ann C. Smith is a genetic counselor who, with colleagues, described the syndrome in 1982. Her clinical work contributed to the first published description of the condition.
Potocki–Lupski syndrome : Potocki–Lupski syndrome is a neurodevelopmental disorder usually caused by a duplication of chromosome 17p11.2. It involves a reciprocal chromosome change in the same region deleted in most Smith–Magenis cases.
Stereotypy : Stereotypy is repetitive, patterned movement or behavior that is not directed toward an obvious goal. Repetitive behaviors, including self-hugging, are recognized features of the syndrome.
17p11.2 deletion : A deletion of genetic material from the short arm of chromosome 17 at band 11.2. This deletion usually removes RAI1 and causes most cases of the syndrome.
Developmental delay : Developmental delay is slower-than-expected acquisition of skills in areas such as movement, communication, or learning. Delays in speech, motor skills, and learning often prompt developmental assessment.
R. Ellen Magenis : R. Ellen Magenis was a physician and geneticist whose work helped characterize chromosome abnormalities and the syndrome named for her. Her chromosome studies helped establish the deletion associated with the condition.
Prader–Willi syndrome : Prader–Willi syndrome is a genetic disorder involving loss of expression of paternally inherited genes on chromosome 15q11–q13. Its sleep, behavioral, and developmental features can overlap, but its genetic cause and clinical pattern differ.
Self-injurious behavior : Self-injurious behavior is deliberate behavior that causes or risks physical harm to oneself. Some affected people develop behaviors such as skin picking or self-biting.
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