Epigenetics/Imprinting

Question 1

• Epigenetics def? Ex?
• Imprinting?
• Molecular basis of imprinting? In transcription region? Effects? (2) How?

Answer 1

• Heritable change in gene expression with out change in DNA sequence (such as post translational change to histones)
• Silencing of autosomal genes aka turned to hemizygotes
• methylation of promotes in 1 of 2 germlines; doesn’t have to be
  1. ) Silencing –> Methylation repels TF’s or attracts repression factors
  2. ) Activation –> Repels repressors

Question 2

• 3 rules of imprinting?
• How do somatic cells keep add methylation after synthesis? How about germ lines?
• Examples of contiguous gene (micro deletion) syndromes related to this? Syndromes?

Answer 2

1. ) Modification occurs when gametes seperate
2. ) Stable after fertilization
3. ) Erased when producing germ cells
   - Maintenance methyltransferase; denovo methyl transferase
4. ) Prader willi = deletion of paternal long 15 = obesity, hypogonadism, almond eyes, sleep apnea (containdication to use GH)
5. ) Angelmans = Deletion of maternal long 15 = unusual face, seizures, spacicity

Question 3

• IDIC? Symptoms?
• Interstitial 15q duplications?
• Downs: Common reason? Amniotic fluid situation? Symptoms? Tests to check = 1st trimester? 2nd? 16 weeks?

Answer 3

• 15q effected, autism, seizures, hypotonia
• Autism if mothers copy only, seizures
• Trisomy 21, extra fluid; brushfield spots, GI tract and heart issues, increased risk of leukemia
  1. ) ultrasound for nuchal folds
  2. ) quad screen
  3. ) Amniocentesis for karyotype