Smith-Magenis syndrome

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BACKGROUND AND CLINICAL INFORMATION: Head

Summary: Smith-Magenis syndrome is characterized by mental retardation and multiple congenital anomalies. A deletion at chromosome 17p11.2 is seen in most patients by cytogenetics or, in smaller deletion, by FISH. The deletion occurs in only one chromosome and almost all of the patients have de novo deletions. Smith-Magenis syndrome is characterized by typical craniofacial features, peripheral neuropathy, mental retardation, and hyperactivity disorder or ADHD. Other typical problems include onychotillomania, spasmodic upper body squeezing, and sleep behavior. Typically, these patients also have aggression, self–destruction, and tantramus. Renal, musculoskeletal, cardiac, and ophthalmological abnormalities may also be present.

Incidence:  1/25,000 in the general population. This can be an underestimation.

Genetics:

Mental and behavial:

Physical features/clinical features:

NEUROIMAGING: Head  

In a small study, about half of the cases have abnormalities. The most common one is ventriculomegaly. Less common abnormalities include by enlargement of cisterna magna and partial absence of the cerebellar vermis.

HISTOPATHOLOGY AND IMMUNOHISTOCHEMISTRY: Head  

Autopsy cases area rarely reported. Abnormal cortical architecture has been described in one case. [Smith AC et al., 1986; Greenberg F et al., 1996]

REFERENCES: Head

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Background    Neuroimaging    Histopathology & Immunohistochemistry    Reference