Bio 362 Human Genetics Spring 2008
Nonclassical inheritance II study sheet for April 29th
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Youssoufian and Pyeritz, 2002
Compare germline and somatic mosaicism. How do you diagnose either condition?
What is the role of reversion mutations in Mendelian disorders? How does it affect the assessment of expressivity for a given disorder?
What is the relationship of mosaicism to cancer?
How does mosaicism affect our assessment of twin phenotypes?
How does chromosomal mosaicism affect our assessment of the phenotypes of chromosomal disorders?
Mechanisms for the generation of mosaicism? What role does selection play?

Leuer et al., 2001
Read the abstract, intro, and discussion only!

Robinson, 2000
What are the ways in which uniparental disomy can arise? Can you determine which mechanism has occurred in a given individual?

Gelb et al., 1998
Why have UPDs for only a subset of chromosomes been discovered easily?
Why was this UPD discovered?
What are the patient's symptoms? How was the actual mutation discovered?
What do Figures 1, 3, and 4 show?
How did this UPD arise?
To learn more about pycnodysostosis, see http://www.medicinenet.com/Script/Main/Art.asp?li=MNI&ArticleKey=462&page=1
(link is also on syllabus online)
Does the patient show any other symptoms?
What do the researchers conclude from that? Is that a valid conclusion? See http://www.geneimprint.com/site/genes-by-species .

Smith et al., 2007, and Wilson et al., 2008
Each of these papers describes two patients with mosaicism of uniparental disomy leading to Beckwith-Wiedemann syndrome. Focus on one of the four patients (as assigned below) and be prepared to explain the data relating to that patient.
Chris and Bill: Smith paper, patient A
Laura and Katie: Smith paper, patient B
Cecie and Philip: Wilson paper, patient 1
Mark and Brady: Wilson paper, patient 2

Non classical inheritance wrap-up
How are the following related?
X-inactivation and mosaicism
X inactivation and imprinting
mosaicism and uniparental disomy
imprinting and uniparental disomy