Modes of inheritance Flashcards
What factors cause variability in presentation for mitochondrial disease?
Number of affected mitochondria-Going over threshold
Age-Number of mitochondria accumulates
Cells with different number of mutated mitochondria
Why do some mitochondria not exist with a disorder when they contain the mutation in copies of their genome?
Mitochondria contain many copies of their genome, some mutant and some normal.
-There is a threshold the mitochondria must be above to exhibit characteristics of the disease
What mode of inheritance may affect all children if their mother is affected?
Mitochondrial inherited disorder
Most likely cause of mitochondrial disease?
Mutation in mtDNA
Y-linked disorder
What type of inheritance affects only males no matter the scenario?
Y-linked disorders
X-linked dominant
What mode of inheritance constitutes that no sons and all daughters of an affected father are affected?
X-linked recessive mutation
What mode of inheritance does haemophilia use?
X-linked recessive
What is odd about the gendered distribution of disease on an X-linked recessive disorder?
-Mainly males will be affected
-Females can be carriers and affected males are linked through females
What is the probability of a daughter of a man with an X-linked condition being a carrier/sufferer of that condition?
100%-Daughters will always inherit their fathers’ X chromosome
What makes a mutation recessive?
Its features won’t be in the phenotype unless it it homozygous
What familial factor increases the risk of transferring autosomal recessive diseases
Consanguineous marriages
What is the probability of offspring inheriting a condition that’s autosomally recessive from 2 carrier parents.
25%
In what mode of inheritance has a ‘carrier’ lost a copy of a single gene yet can maintain normal function
Autosomal recessive
What is the mode of inheritance of huntingtons’ disease and outline its mechanism of action
Huntingtons is autosomal dominant
-It is caused by unstable CAG repeats within chromosome 4, leading to accumulation of huntingtin and toxic cell death
Through what mode of inheritance is a phenotype manifested if the allele is present in a heterozygote?
Autosomal dominant
Outline the 3 autosomal dominant disorders types
Gain-of-function: Gene now makes a protein with a different, unwanted function
Dominant negative effect: The mutated form interferes with protein activity which it binds to.
Haploid insufficiency: Loss of one copy of the gene, so not enough protein for normal function can be made
