Imprinting (15.1)

Question 1

Imprinting

Answer 1

biological phenomenon in which certain genes are expressed in a parent-of-origin-specific manner due to epigenetic modifications

Question 2

Maternally imprinted

Answer 2

Some genes are turned off in the chromosomes inherited from our mother. Gene on the maternally inherited allele is transcriptionally silent. THe paternally inherited allele is expressed

Question 3

Paternally imprinted

Answer 3

Some genes are turned off in the chromosomes inherited from our father. Gene on the paternally inherited allele is transcriptionally silent. The maternally inherited allele is expressed.

Question 4

Expression levels and phenotypes for Igf2 and Igf2R for a mouse

Answer 4

Igf2=Igf2R Normal size mouse
Igf2> Igf2R Large sized mouse
Igf2<Igf2R Small sized mouse

Question 5

Prader-Willi syndrome

Answer 5

Imprinting disorder
delated intellectual disability flaccid muscles, hormonal imbalances leading to:
Short stature, compulsive behavior, constant hunger and delayed puberty
PW genes are maternally imprinted

Question 6

Angelman’s syndrome

Answer 6

Imprinting disorder
Delayed development, intellectual disability, severe speech impairment, happy demeanor, ataxia
Angelman genes are paternally imprinted

Question 7

What is a common cause of PEW and As?

Answer 7

de novo deletion of regions on chromosome 15 that removes both the PS and A genes. This de novo mutation occurs during meiosis