Genetic Basis of Complex Inheritance

Question 1

What is complex inheritance?

Answer 1

Inheritance that does not follow mendelian inheritance

Question 2

What are some inheritance patterns of complex inheritance?

Answer 2

Incomplete penetrance

Genomic imprinting

Extranuclear inheritance

Anticipation

Question 3

What is incomplete penetrance?

Answer 3

People have a mutation but do not develop the symptoms of the disorder

Question 4

What is genomic imprinting?

Answer 4

Genes expressed only from one chromosome, parent of origin dependent

(maternal or paternal gene is switched of)

Question 5

What is extranuclear inheritance?

Answer 5

Transmission of genes that occur outside the nucleus, such as the mitochondria

Question 6

What is anticipation?

Answer 6

Symptoms of a genetic disorder become apparent at an early age

Question 8

What is penetrance?

Answer 8

The frequency with which a trait is manifested by individuals carrying the gene

Question 9

What gene is usually responsible for cystic fibrosis?

Answer 9

CFTR

Question 10

What are genetic modifiers?

Answer 10

Genes that have small quantative effects on the level of expression of another gene

Question 11

What is polymorphism?

Answer 11

Genetic variants of a gene

Question 12

What is also important for the onset of genetic diseases?

Answer 12

Environmental factors

Question 13

What are epigenetic modifications?

Answer 13

Heritable changes in gene function that cannot be explained by changes in DNA sequences

Question 14

What is uniparental disomy?

Answer 14

2 copies of a chromosome come from the same parent instead of 1 from each

Question 15

What are the 2 kinds of uniparental diploidy?

Answer 15

Gynotypic (2 maternal genomes)

Androgenic (2 paternal genomes)

Question 17

What is gynogenic uniparental diploidy?

Answer 17

2 maternal genomes:

Mass of embryo

Ovarian teratoma

Question 18

What is andogenic uniparental diploidy?

Answer 18

2 paternal genomes:

Mass of placenta

Hydatidiform mole

Question 19

What are examples of imprinting disorders?

Answer 19

Angelman syndrome

Prader-Willi syndrome

Question 20

Where is mitochondiral inheritance from?

Answer 20

Maternal

Question 21

Which has more mutations out of the nuclear genome and the mitochondria?

Answer 21

Mitochondria due to:

Lack of DNA repair systems

Lack of protective proteins such as histones

Damaged by reactive oxygen species

Question 22

What is polyploidy?

Answer 22

Cell having more than 2 pairs of chromosomes

Question 23

What is homoplasmy?

Answer 23

Cell whose mitochondrial DNA is all identical

Question 24

What is heteroplasmy?

Answer 24

Cells whose mitochondrial DNA is not all identical

Question 25

What are the 3 major myopathies?

Answer 25

Myoclonic epolepsy

Mitochondrial myopathy

Chronic progressive external ophthalmoplegia

Question 26

What does mitochondrial disease affect?

Answer 26

Tissues with high metabolic demand

Question 27

How can a baby have 3 genetic parents?

Answer 27

Sperm from dad

Egg from a mum

Mitochondrial DNA from another mum

Question 28

What are examples of anticipation diseases?

Answer 28

Triple repeat diseases:

Huntington’s disease

Myotonic dystrophy

Fragile X syndrome