Smith
Magenis SyndromeSmith Magenis syndrome is due to a mutation of the RAI
1 gene on chromosome 17 in the fetus affecting 1 in 25,000 births. It results
in multi organ abnormalities. People affected with this syndrome have problems
with speech development and language skills. They suffer from mild to moderate
mental retardation, behavior disturbances and sleep disorders. Here is an image
of a mother
and her child with the syndrome. Signs and symptoms
There is a square
face with deep-set eyes. The chin is prominent, the bridge of the nose flattened.
The mouth tends to be turning downwards. These facial features often develop only
later in life. People with Smith Magenis syndrome have problems falling asleep
and tend to wake up several times per night, so they often are very sleepy during
the day. Although they have affectionate personalities, they also suffer from
impulsiveness, temper tantrums and anger outbursts. They engage in self-injurious
practices such as head banging, skin picking, hitting and biting. They tend to
lick their fingers and compulsively turn pages in books or magazines (“lick
and flip” behavior). Small stature and scoliosis (spinal curvature) is common.
Short-sightedness (myopia) is frequently noticed.. The can also have ear deformities
and hearing loss. Heart and kidney deformities are also common. Diagnostic
tests Chromosomal analysis on cultured lymphocytes shows the deletion
on the short arm of chromosome 17 using the fluorescence in situ hybridization
(FISH) with DNA probes specific for the 17p11.2 gene location. Prognosis
Depending on how severe the mental retardation is and what life threatening
heart or kidney abnormalities are present, the individuals may have a higher mortality
in the earlier years. The ones who survive longer usually have less abnormalities
and may have less severe mental retardation, the degree of which will determine
whether they will to be placed in a care home or not.
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