1. Chromosomal Microdeletions: Prader-Willi and Angelman Syndromes

2. Prader-Willi Syndrome
Gene imprinted (turned off)
Gene not imprinted (turned on)
Maternal DNA
Paternal DNA D e l t d
Prader-Willi Syndrome D e l t d
Angelman Syndrome

3. http://www. ncbi. nlm. nih. gov/books/bv. fcgi. tool=bookshelf&call=bv

5. 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)

6. Prader Willi Syndrome

7. Tanis, a girl with PWS

8. Angelman Syndrome Cause: Symptoms:
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)

9. Angelman
Syndrome

10. Angelman Syndrome