Categories and impact of genetic disease - GiM Flashcards
what are the 3 factors that determine the aetiology of a disease?
1) Environment
2) Polygenic
3) Single gene
Give an example of an environmental disease?
Scurvy
*due to lack of vit C
Give an example of a genetic disease?
Duchene muscular dystrophy
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”
Multifactorial (complex)
The following definition describes Multifactorial (complex) / single gene / chromosomal / mitochondrial / somatic mutations ??
“A mutation in a single gene = Mendelian inheritance e.g. cystic fibrosis”
Single gene
The following definition describes Multifactorial (complex) / single gene / chromosomal / mitochondrial / somatic mutations ??
“an imbalance or rearrangement in chromosome structure e.g. aneuploidy, deletion , translocation”
Chromosomal
The following definition describes Multifactorial (complex) / single gene / chromosomal / mitochondrial / somatic mutations ??
“A mutation in mitochondrial DNA”
Mitochondrial
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
Somatic Mutation
How many pairs of chromosomes does a diploid cell have?
23 pairs of chromosomes in a diploid cell
In what type of inheritance are males and females equally affected?
1) Autosomal Dominant inheritance
2) Autosomal Recessive
3) Mitochondrial inheritance
In what type of inheritance does offspring of an affected person have a 50% (1 in 2) chance of inheriting the mutation?
Autosomal Dominant Inheritance (AD)
How are the following diseases inherited?
- Myotonic Dystrophy
- Marfan Syndrome
- Huntingtion Disease
Autosomal Dominant (AD) inheriance
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”
Penetrance
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”
Expressivity
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”
Anticipation
what is a de novo mutation / new dominant mutatiion?
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)
In what type of inheritance is there a 25% (1 in 4) risk of offspring being affected?
Autosomal Recessive Inheritance
How are the following diseases inherited?
- cystic fibrosis
- sickle cell
- haemachromatosis
Autosomal recessive
In what type of inheritance are males predominantly affected?
X-linked recessive
How are the following diseases inherited?
- Duchene Muscular dystrophy
- Red/green colour blindess
- Haemophilia
- Fragile X syndrome
X linked recessive
What is X inactivation?
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.
What is X-linked dominant?
only one X chromosome needs to carry the gene so females also affected.
What type of inheritance is in Rett syndrome?
X-linked dominant
lethal in males, females express phenotype
