Inheretance Of Human Disease Flashcards
Penetrance
The likelihood of having a disease if you have a pathogenic variant
Autosomal dominant
Only one copy required to cause disease.
Seen in all generations
50% chance of passing mutated gene to child
Autosomal recessive
2 copies required to cause disease
Often only 1 generation affected
1 in 4 risk of child being affected if parent carries
How does 1 copy of an affected x linked recessive allele affect males and females?
Female with one affected allele does not show major clinical features
Male with faulty allele will be fully affected
How likely is a female with one affected X chromosome to have affected children?
25% unaffected son
25% affected son
25% unaffected daughter
25% carrier daughter
If a male with an affected X chromosome has children how will his children be affected?
All daughters will be carriers
All sons will be unaffected
Why can female carriers show mild features with an affected X chromosome?
Due to X chromosome inactivation
Around half of cells will have faulty gene
Polymorphism
Genetic variant that does not by itself cause a disease
How is mitochondrial DNA transmitted?
Maternally
In the ovum
Amount of mutation in the mitochondrial genome:
Only present in a proportion of the mitochondria
Proportion varies between cells
How mutations cause disease: Haploinsufficiency
Only one copy of working gene
Reduced protein production
How mutations cause disease:
Dominant negative
Expression of abnormal protein interferes with normal protein
How mutations cause disease:
Gain of function
Mutant protein gains a new function affecting cell processes
How mutations cause disease:
Complete loss of function
Autosomal recessive
2 copies of faulty gene produces no protein
Precision medicine
Using testing to identify a subgroup of patients who respond to treatment
Most effective for rare diseases and high penetrance mutations
Imprinting
Differences in gene expression depending on wether the gene is paternally or maternally inherited
