Chromosomal Microdeletions: Prader-Willi and Angelman Syndromes

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Chromosomal MicrodeletionsPrader-Willi and
Angelman Syndromes
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(No Transcript)
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http//www.ncbi.nlm.nih.gov/books/bv.fcgi?toolboo
kshelfcallbv.View..ShowSectionsearchtermprader
ridgnd.section.182
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http//www.mgm.ufl.edu/faculty/DDriscoll.htm
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Prader-Willi Syndrome
Cause

• Usually caused by micro deletion in region q11-13
  of the paternally transmitted chromosome 15.
• Several genes in this region are genomically
  imprinted in the maternal chromosome.
• Hence, if there is a paternal deletion in this
  region, there are no active genes.

Symptoms

• Short stature
• Mental retardation, learning difficulties
• Decreased muscle tone
• Hypogonadism
• Emotional lability
• Unregulated appetite or hyperphagia (? obesity)

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Prader Willi Syndrome
http//www.bmb.psu.edu/faculty/simpson/lab/07impri
/pws.jpg
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Tanis, a girl with PWS
http//www.bmb.psu.edu/faculty/simpson/lab/07impri
/pws.jpg
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Angelman Syndrome
Cause
Microdeletion of region q11-13 of chromosome 15
that deletes agene(s) that is paternally
imprinted.
Symptoms

• Normal development until 6-12 months, then
  delayed development
• Disproportionate head growth ? microcephaly
• Abnormal EEG, seizures
• Marked deficit in language (no words to a few
  words) but better communication using nonvebral
  methods (e.g., facial expressions)
• Motoric problems (balance problems, ataxia of
  gait, hypermotoric actions)
• Attention problems (short attention span)
• Emotional exuberance (frequent laughter, smiling)

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Angelman Syndrome
http//asclepius.com/angel/phopag.html
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Angelman Syndrome
http//asclepius.com/angel/phopag2.html