Download HGSS_Chapter8_PWSAng

Chromosomal Microdeletions:
Prader-Willi and Angelman
Syndromes
Gene imprinted (turned off)
Gene not imprinted (turned on)
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Maternal
DNA
Paternal
DNA
Prader-Willi
Syndrome
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Angelman
Syndrome
http://www.ncbi.nlm.nih.gov/books/bv.fcgi?tool=bookshelf&call=bv.View..ShowSecti
on&searchterm=prader&rid=gnd.section.182
http://www.mgm.ufl.edu/faculty/DDriscoll.htm
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)
Prader Willi Syndrome
http://www.bmb.psu.edu/faculty/simpson/lab/07impri/pws.jpg
Tanis, a girl with PWS
http://www.bmb.psu.edu/faculty/simpson/lab/07impri/pws.jpg
Angelman Syndrome
Cause:
Microdeletion of region q11-13 of chromosome 15 that deletes a
gene(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)
Angelman
Syndrome
http://asclepius.com/angel/phopag.html
Angelman Syndrome
http://asclepius.com/angel/phopag2.html