genetic basis of complex inheritance Flashcards
what is penetrance?
the frequency with which a trait is manifested by individuals carrying the gene
what gene is responsible for patients manifesting cystic fibrosis?
CFTR
what are genetic modifiers?
genes that have small quantitative effects on the level of expression of another gene
what is uniparental disomy?
inheritance of a chromosome pair from one parental origin
what is genomic imprinting?
genes are expressed from only one chromosome (parent) e.g. if the gene from the father is imprinted it is silenced and only the allele inherited from the mother will be expressed
what is gynogenic uniparental diploidy?
2 maternal genomes
what is androgenic uniparental diploidy?
2 paternal genomes
where is mitochondrial DNA inherited from?
mother
how many more times likely is it that there will be a mutation in the mitochondrial DNA compared to the nuclear genome?
100 times more likely
why is the mitochondrial DNA more likely to mutate?
lack of efficient DNA repair system
lack of protective proteins, such as histones
damaged by reactive oxygen species, such as free radicals
what is homoplasmy?
uniform mitochondrial DNA
what is heteroplasmy?
two or more types of mitochondrial DNA?
when is disease likely to occur in heteroplasmy?
when there is a high percentage of mitochondrial mutation
what are the 3 myopathies that occur in mitochondrial disease?
myoclinic epilepsy with ragged red fibers (MERRF)
mitochondrial myopathy, encephalomyopathy, lactic acidosis, stroke like symptoms ( MELAS)
chronic progressive external opthalmoplegia (CPEO)
