Mitochondrial Genetics And Forensic DNA Analysis Flashcards
Defects
Can be due to autosomal, X-linked mutations or mutations in mitochondrial DNA
Higher mutation rate in mitochondrial DNA
Mitochondrial diseases
Mutations of ox/phos
Most serious in CNS and muscles
Neuropathies, encephalopathies, myopathies
Matrilineal inheritance
Mitochondria come from mom because egg is much larger than sperm and contributes both cytoplasm and nucleus to zygote
Homoplasmy
Population of mitochondria that all have the same genetic composition
If mother is homoplasmic, all children should inherit same mitochondria
Heteroplasmy
2 or more different population of mitochondria present in cell
Different in expression of same disease due to random separation of mitochondrial population to children, also need at least 85% of mutant mitochondria to express dysfunction
Replicative segregation
As cells divide, relative proportions of mutant mitochondria may change over time
Disorders often progressive with late onset because of increase over time in number of mutations per cell and number of mutant cells
Forensic DNA analysis
Sources of error include quality of specimen, statistical analysis, and interpretation (polymorphisms vary between different populations, races, ethnic groups)
Nuclear DNA analysis: has hypervariable mini satellite regions, for DNA fingerprinting, individual identification, twin studies, paternity test, criminal justice
Mitochondrial DNA analysis: link individuals by comparing maternal mitochondrial lineages, for family identity not individual