Prader Willi Syndrome Flashcards
A genetic evaluation in Prader Willi (PWS) will include a _________ karyotype.
Normal
A FISH test for PWS will test ______ for deletion of Chr __________.
positive; 15q11-q13
During preschool age, feeding difficulties in children w/ PWS will _______.
Reverse; the children will then develop hyperphagia and gain weight.
PWS results when genetic info is missing from the (paternal or maternal) allele of Chr________.
Paternal; 15q11-q13
PWS may result because: (3 reasons)
- deletion of paternal allele; 2. uniparental disomy (2 copies present from only mom); 3. Imprinting error in how alleles are marked, causing virtual maternal UPD (leadingbody to think that Chr is missing.
A deletion in the maternal allele in 15q results in what disorder?
Angelman syndrome
Other problems associated with Chr 15q?
Maternally inherited 15 q interstitial duplication, isodicentric isochromosome 15q (IDIC 15), Marker chromosomes (inverted duplication), deletions (Angelman Syndrome)
The maternal and paternal alleles are marked by different patterns of _________.
Methylation
Testing for PWS
- Methylation testing of Chr 15 for deletion; 2. If deletion present; a FISH test or a microarray can be done to confirm diagnosis.
Infancy PWS Characteristics
Hypotonicity, almond shape eyes, undescended testicles, severe feeding problems (need Gtube), lighter pigmentation than family members.
Toddler/Preschooler PWS Characteristics
Usually btwn ages 2-4, feeding problem reverses, become obese b/c don?t ever feel sated unless treated with growth hormone
Eye Medical Issues in PWS
Strabismus (lazy eye), and Nystagmus (jiggly eyes)
Orthopedics Medical Issue in PWS
Scoliosis
Respiratory Medical Issue in PWS
Obstructive Sleep Apnea (contraindication to use of growth hormone)
Developmental Issues in PWS
mild-moderate cognitive disabilties usually found, and behavioral issues are common
It has been reported that a linkage disequilibrium between pts with Autism and Polymorphisms occurs in ________ locus on Chr 15.
GABAa-b3
gamma-aminobutyric acid type A is an important ______ in the CNS, and is synthesized from the GABAa-b3 locus.
neurotransmitter
What chromosome anomaly is one of the most frequently reported cytogenic abnormalities in patients with Autism?
Maternally derived proximal 15q11-q13 (supernumerary marker Chr, IDIC 15)
What are the phenotypes in pts with Chr anomaly, Inverted Duplicated Isocentric 15q (IDIC 15)?
Autism, NOT dysmorphic, often hypotonic, seizures common
15q interstitial duplication can result in what anomaly?
partial Trisomy
The 15q interstitial duplication of 15q does NOT have a phenotype if it is inherited from the _______.
father
Maternally derived interstitial 15q duplications experiences what phenotype?
Autism, NOT dysmorphic, often hypotonic during infancy, seizures common (Similar to IDIC 15)
Phenyotype of Angelman Syndrome
Mildly dysmorphic facial features which evolve with age, hypotonia in infancy that progresses to spasticity in older patients, intellectual disability, seizures and autism.
