Gene Dosing and Imprinting

Question 1

What is the name given to inactivated X chromosomes that are seen microscopically?

Answer 1

Barr bodies

Question 2

What is uniparental disomy?

Answer 2

When to imprinting for one chromosome region is copied to the other leaving only maternal or only paternal imprinted genes

Question 3

What is the pattern of passing down of gender specific imprints to gametes?

Answer 3

Female imprinted genes are passed to oocytes while male imprinted genes are passed to sperm

Question 4

What causes Bechwith-Wiedemann syndrome?

Answer 4

60% is epimutation in maternally imprinted alleles

Question 5

Which X-chromosome is inactivated in females, the maternally or paternally inherited one?

Answer 5

Both, it’s different in different cells

Question 5

What does parthenogenetic refer to?

Answer 5

Receiving two maternally imprinted alleles for a gene

Question 5

Epimutation results in what?

Answer 5

Loss of gender imprinting

Question 6

What does bi-allelic expression refer to?

Answer 6

Alleles for a gene are expressed on both chromosomes

Question 7

Which chromosome is replicated in Down syndrome?

Answer 7

21

Question 8

What is the mechanism for inactivating an X-chromosome in females?

Answer 8

DNA methylation

Hyperchromatin structure

Non-coding RNAs

Question 8

What does loss of heterozygosity refer to?

Answer 8

Microdeletion of one allele containing the imprinted genes

Question 9

What is genomic imprinting?

Answer 9

Whereby the parental origin of a particular gene is marked by reversible epigenetics

Question 10

What is the result of most trisomy’s?

Answer 10

Miscarriage

Question 12

What trisomy is the cause of Edwards syndrome?

Answer 12

18

Question 13

What is the name for this condition with this karyotype, 45,X

Answer 13

Turner syndrome

Question 15

In which chromosome pair is a monosomy viable?

Answer 15

The sex chromosomes

Question 16

What is haploinsufficiency?

Answer 16

Where one copy of a gene is insufficient to support normal cell function therefore fetal development

Question 17

What is aneuploidy?

Answer 17

Unbalanced set of chromosomes

Question 17

Apart from intellectual disability what is the major deficit in Down syndrome patients?

Answer 17

Congenital heart disease

Question 18

What causes Prader-Willi syndrome?

Answer 18

Deficiency of paternal expressed genes

Question 20

How does Edwards syndrome present?

Answer 20

Characteristic overlapping fingers and club-like hand

Congenital heart disease

Development disability

Question 21

What causes Angelman syndrome?

Answer 21

Deficiency in maternally expressed genes responsible for AS

Question 23

What does androgenic refer to?

Answer 23

Receiving two paternally imprinted alleles for a gene

Question 24

What is the most common cause of aneuploidy?

Answer 24

Chromosome non-disjunction of homologous chromosomes - failure of a chromosome to separate into a new cell during cell division

Question 25

What is the parental conflict hypothesis?

Answer 25

Maternally inherited genes tend to limit fetal growth to conserve energy while paternally inherited genes tends to promote fetal growth