Categories and impact of genetic disease - GiM

Question 1

what are the 3 factors that determine the aetiology of a disease?

Answer 1

1) Environment
2) Polygenic
3) Single gene

Question 2

Give an example of an environmental disease?

Answer 2

Scurvy

*due to lack of vit C

Question 3

Give an example of a genetic disease?

Answer 3

Duchene muscular dystrophy

Question 4

The following definition describes Multifactorial (complex) / single gene / chromosomal / mitochondrial / somatic mutations ??

“The interaction of multiple genes in combination with environmental factors e.g. type 2 diabetes, ischemic heart disease”

Answer 4

Multifactorial (complex)

Question 5

The following definition describes Multifactorial (complex) / single gene / chromosomal / mitochondrial / somatic mutations ??

“A mutation in a single gene = Mendelian inheritance e.g. cystic fibrosis”

Answer 5

Single gene

Question 6

The following definition describes Multifactorial (complex) / single gene / chromosomal / mitochondrial / somatic mutations ??

“an imbalance or rearrangement in chromosome structure e.g. aneuploidy, deletion , translocation”

Answer 6

Chromosomal

Question 7

The following definition describes Multifactorial (complex) / single gene / chromosomal / mitochondrial / somatic mutations ??

“A mutation in mitochondrial DNA”

Answer 7

Mitochondrial

Question 8

The following definition describes Multifactorial (complex) / single gene / chromosomal / mitochondrial / somatic mutations ??

“mutation(s) within a gene(s) in a defined population of cells that results in disease e.g. breast cancer

Answer 8

Somatic Mutation

Question 9

How many pairs of chromosomes does a diploid cell have?

Answer 9

23 pairs of chromosomes in a diploid cell

Question 10

In what type of inheritance are males and females equally affected?

Answer 10

1) Autosomal Dominant inheritance
2) Autosomal Recessive
3) Mitochondrial inheritance

Question 11

In what type of inheritance does offspring of an affected person have a 50% (1 in 2) chance of inheriting the mutation?

Answer 11

Autosomal Dominant Inheritance (AD)

Question 12

How are the following diseases inherited?

• Myotonic Dystrophy
• Marfan Syndrome
• Huntingtion Disease

Answer 12

Autosomal Dominant (AD) inheriance

Question 13

Is the following definition in regards to penetrance or expressivity?
“The frequency with which a specific genotype is espressed by those individuals that possess it, usually given as a percentage”

Answer 13

Penetrance

Question 14

Is the following definition in regards to penetrance or expressivity?
“Variation in expression - the extent to which a heritable trait is manifested by an individual”

Answer 14

Expressivity

Question 15

Is the following definition in regards to penetrance or anticipation?
“The symptoms of a genetic disorder become apparent at an earlier age as it is passed from one generation to the next. In most cases there is an increase in the severity of symptoms too”

Answer 15

Anticipation

Question 16

what is a de novo mutation / new dominant mutatiion?

Answer 16

a new mutation that has occured during gametogenesis or in early embryonic development.

(parents nor affected. Child is first to be affected and can pass on the mutation)

Question 17

In what type of inheritance is there a 25% (1 in 4) risk of offspring being affected?

Answer 17

Autosomal Recessive Inheritance

Question 18

How are the following diseases inherited?

• cystic fibrosis
• sickle cell
• haemachromatosis

Answer 18

Autosomal recessive

Question 19

In what type of inheritance are males predominantly affected?

Answer 19

X-linked recessive

Question 20

How are the following diseases inherited?

• Duchene Muscular dystrophy
• Red/green colour blindess
• Haemophilia
• Fragile X syndrome

Answer 20

X linked recessive

Question 21

What is X inactivation?

Answer 21

X inactivation is normal and occurs when there is 2 or more X chromosomes in a cell.

approx 50% of cells express the normal gene.

Question 22

What is X-linked dominant?

Answer 22

only one X chromosome needs to carry the gene so females also affected.

Question 23

What type of inheritance is in Rett syndrome?

Answer 23

X-linked dominant

lethal in males, females express phenotype