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
