Lecture 8: Mitochondrial Genetics and Forensic Analysis Flashcards
A woman is heteroplasmic for a mutation in the mito gene which is assocd with MERFF syn. List 3 factors that’ll influence whether or not her children will be affected with MERFF.
The freq of the different alleles, which mutations each child inherits, which tissues are involved.
Why are mitochondrial diseases often progressive with late onset? Explain a mechanism that accounts for this.
Due to an increase, over time, in the numbers of mutations per cell and the numbers of mutant cells. Replicative segregation - as cells divide, the relative proportions of mutant mitochondria may change over time; the freq of mutation within a clone can inc or dec.
What are the preferred requirements when doing a family mito DNA analysis?
Obtain sample from proband, mother, and at least one other indiv who’s maternally related to the proband (sibling, maternal gma).
Mito mutations usually are related to tissues with a high degree of ox/phos activity. Name three common general types of disorders.
Neuropathies, encephalopathies, myopathies.
Homoplasmy
Population of mitochondria that all have the same genetic composition; all the mito’s are the same within a given cell.
Heteroplasmy. What implications does this have within families with a mitochondrial disease?
Heterozygosity for one or more cytoplasmic genes. There may be a difference in the expression of the same disease.
Use of DNA technologies (PCR, RFLP, sequencing etc) to obtain info on the genetic identity of an indiv and how that relates to a criminal, medical, or scientific investigation.
Forensic DNA Analysis
To uniquely identify the DNA, what regions of the DNA should you examine? What regions in the nuclear DNA have the most variability and thus are used in DNA fingerprinting?
Those that have the highest degree of polymorphism. Hypervariable minisatellite regions.
