Clinical Presentation
Classic eating related symptom in Prader Willis?
What is Hyperphagia
What is the most common cause of PWS
de novo deletion; accounts for about 70%
Name one gene involved in PWS
SNRPN, NDN, many other genes
What is a symptom common to both PWS and Angelman?
Intellectual/Learning Disabilities
Why should Paulette's father not blame himself?
Because the deletion occurred de novo
Why does PWS cause hypogonadism despite gonads being structurally normal?
Hypothalmic dysfunction disrupting gonadotropin releasing hormone
Which etiology of PWS carries the highest risk of recurrence?
Imprinting Control Defects; specifically a microdeletion that is not de novo
Despite an error in meiosis, the zygote ends up with 2 chromosomes instead of 3 due to this mechanism
Trisomy Rescue
What does UBE3A code for and what is its function?
Ubiquitin ligase and it is responsible for protein degradation in brain development
T/F Methylation analysis can be used to confirm which etiology is causing PWS
False
A 3 y/o boy presents with seizures, ataxia, and episodes of inappropriate laughing with near-absent speech. What is the most likely diagnosis?
Angelman's Syndrome
Explain how unipolar disomy can cause both PWS and Angelman's Syndrome
PWS - maternal UPD as maternal chromsomes are silenced
AS - paternal UPD as paternal chromosomes are silenced
In imprinting, a methyl group is attached to which nucleotide
Cytosine
A chromosome 15q11-q13 deletion is identified in two siblings. One has PWS, the other has Angelman syndrome. How is this possible?
Sibling One inherited the deletion from their father (PWS) and the Sibling 2 inherited the deletion from their mother (AS).
FISH is useful for determining which etiology in PWS
de novo deletion