Epigenetics

Epigenetics

• The study of heritable changes in phenotype or gene expression caused by mechanisms other than changes in the underlying DNA sequence

Types Of Epigenetic Changes

• DNA Methylation

• Histone Modification

• Non-Coding RNA/Silencing

Histone Modification

• The binding of different chemical groups to histone “Tails” alters the extent to which DNA is wrapped around histones and the availability of genes to be activated

DNA Methylation

• Methylation of DNA at CpG sites can inactivate gene expression

Genomic Imprinting

• People inherit two copies of their genes = One from their mother and one from their father

  • Usually both copies of each gene are active, or “Turned on” in cells

• Genomic imprinting = In some cases, however, only one of the two copies is normally turned on

  • Which copy is active depends on the parent of origin = Some genes are normally active only when they are inherited from a person’s father

  • Others are active only when inherited from a person’s mother

Prader-Willi Syndrome

• Missing gene activity that comes from paternal side

  • Father’s copy is missing, or have two maternal copies

Prader-Willi Syndrome S/S

• Learning difficulties, short stature, compulsive eating

Angelman Syndrome

• Missing gene activity that comes from maternal side

  • Mother’s copy is missing, or have two paternal copies

Angelman Syndrome S/S

• Learning difficulties, speech problems, seizures, jerky movements