Chromosomal Microdeletions:

Prader-Willi and Angelman Syndromes

PaternalDNA

MaternalDNA

Deleted

Prader-WilliSyndrome

Deleted

AngelmanSyndrome

Gene imprinted (turned off)

Gene not imprinted (turned on)

http://www.ncbi.nlm.nih.gov/books/bv.fcgi?tool=bookshelf&call=bv.View..ShowSection&searchterm=prader&rid=gnd.section.182

http://www.mgm.ufl.edu/faculty/DDriscoll.htm

•Usually caused by micro deletion in region q11-13 of the paternallytransmitted chromosome 15.

•Several genes in this region are genomically imprinted in the maternalchromosome.

•Hence, if there is a paternal deletion in this region, there are no active genes.

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

Cause:

Symptoms:

Prader-Willi Syndrome

http://www.bmb.psu.edu/faculty/simpson/lab/07impri/pws.jpg

Prader Willi Syndrome

http://www.bmb.psu.edu/faculty/simpson/lab/07impri/pws.jpg

Tanis, a girl with PWS

•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)

Symptoms:

Angelman Syndrome

Cause:Microdeletion of region q11-13 of chromosome 15 that deletes agene(s) that is paternally imprinted.

http://asclepius.com/angel/phopag.html

AngelmanSyndrome

http://asclepius.com/angel/phopag2.html

Angelman Syndrome