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. They 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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