Genetic basis of complex inheritance

Question 1

What rule does Mendelian inheritance follow

Answer 1

Law of dominance
The Law of Segregation
The Law of Independent Assortment.

Question 2

An intermediate phenotype is a result of

Answer 2

Non mendelian inheritance

Question 3

What are the factors contracting to non mendelian inheritance

Answer 3

Incomplete penetrance
Genomic printing from parental genes
mitochondria mutations
anticipation

Question 4

Define penetrance

Answer 4

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

Question 5

What is an example of a disease thats shows 100% penetrance

Answer 5

cystic fibrosis

CFTR mutation

Question 6

What two factors contribute to the severity of a mutational human disease

Answer 6

Genetic modifiers

Environmental Factors

Question 7

Define Genomic imprinting

Answer 7

only certain genes are expressed from parents e.g. if the allele inherited from the father is switched of silenced only the allele from the mother is therefore expressed

Question 8

Define Bi-allelic

Answer 8

Both parental genes are expressed

Question 9

What is uniparental disomy

Answer 9

Inheritance of chromosomal pair from one of the parental

Question 10

What is a genetic modifier

Answer 10

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

Question 11

What are Epigenetic modifications

Answer 11

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

Question 12

what do imprinted genes have a higher risk of

Answer 12

genetic disease

Question 13

How can Imprinting errors occur

Answer 13

Deletion

Uniparental disomy

Question 14

What are the three pathways that can cause Uniparental disomy

Answer 14

Trisomy/monsomy rescue

mitotic error

Question 15

What are examples of uniparental disomy disorders

Answer 15

Gynogenic (2 maternal= ovarian teratoma)

Androgenic (2 parental = Hydatidiform mole, womb mass)

Question 16

What are examples of imprinting disorders within chromosomal region 15q11-13

Answer 16

Angelman syndrome - paternal

Prader willi syndrome - maternal

Question 17

Why is the mitochondria a mutational hotspot

Answer 17

lack of efficient DNA repair system
Lack of protective proteins
damage by free radicals

Question 18

What is homoplasmy and heteroplasmy

Answer 18

no mutated mitochondria

mutated mitochondria

Question 19

Where are mitochondrial diseases most likely to occur

Answer 19

tissue with high metabolic demand = myopathies

Question 20

what are the examples of mitochondrial diseases

Answer 20

Diabetes mellitus and deafness (DAD)
Leber’s hereditary optic neuropathy (LHON) -loss of central vision
Leigh’s syndrome - neurological disorder

Question 21

What is anticipation

Answer 21

Disease presents at earlier age become more apparent with each generation and can increase severity in succeeding generations.

Question 22

Example of anticipation triplet repeat expansion

Answer 22

Huntington’s disease
Myotonic dystrophy
Fragile X syndrome

Question 23

what happens in triple repeat diseases

Answer 23

Mutated triplet ions located everywhere and during meiosis, unstable repeats can undergo triplet expansion therefore the germ cells produce greater number of repeats than are found in the somatic tissues