User:Jpate46/sandbox

I intend to update the mitochondrial disease page with methods that are used for treating such diseases, and possibly add a subsection on managing the disease under treatments. I believe that the page can benefit from perhaps a more detailed look at diagnosis as well.

Mitochondrial Disease Additions:

Diagnosis

The general approach to diagnosing mitochondrial disease is usually fairly straightforward, especially if there is a recognizable physical manifestation of the disease, along with a known family history. Usually, a three-generation family history would be required in order to establish that the patient is suffering from a mitochondrial disease. Paired with molecular genetic testing (such as mitochondrial genome sequencing), these two make for a reliable diagnosis. Methods to improve prognosis of mitochondrial disease that are a directly linked to mitochondrial genome mutation or to certain variants include early detection using methods such as chorionic villus biopsy. Chorionic villus biopsy has been used in the past to detect heteroplasmic mtDNA prenatally.

Link to Cancer

Somatic mitochondrial DNA mutations have also been associated with cancer, and have been found in many solid tumours and leukemias.

Mitochondrial Donation

The inheritance of defective mitochondria have the implicated as cause for genetic disease from birth. Mitochondria are passed down to a child by the mother, so if a mother passes down faulty mitochondria, the child would develop disease. Therefore, replacement of faulty mitochondria in an embryo is an effective method of "curing" the disease before the child is born. Also known as three-person IVF, mitochondrial donation is a method in which a in-vitro fertilized zygote is given the mitochondria of a third party. As of February 24th, 2015, these methods are legal within the United Kingdom. And as of January 27th, 2015, the United States Institute of Medicine had set up a committee at the Food and Drug Administration's request to study the implications of the use of these techniques. Currently, the techniques used include:

• Pronuclear transfer:
  • Where an embryo is created via IVF with the mother and father's gametes, and simultaneously, a second donor embryo is created using a donor egg (with healthy mitochondria) and the father's sperm. Then while the embryos are still at the single cell stage, the pronucleus of the donor embryo is replaced by the pronucleus of the parent's embryo. Thus, creating an embryo that does not have the mother's defective embryo.

• Maternal spindle transfer:
  • Nuclear DNA is removed form the mother's egg, and the rest of the egg is disposed of (including the unhealthy mitochondria). The nuclear DNA of an egg from a healthy donor is removed and replaced with the mother's egg's nuclear DNA. This results in the creation of an embryo with healthy mitochondria.

• Nuclear genome transfer:
  • This method is essentially the same as maternal spindle transfer, however, has a higher success rate.

• Polar body genome transfer.
  • Polar bodies are generated in the process of creating human egg cells. They contain a genome but do not have a mitochondria. This method involves the transfer of polar body genome into a donor egg cell. This is an experimental technique but is thought to reduce the change of accidental transfer of faulty mitochondria from the mother.

Possible problems with mitochondrial donation include:

• Epigenetic harm caused by nuclear transfer
• Mito-nuclear mismatch (where donated mitochondrial and the recipient cell do not work well with each other)
• Preferential replication of even tiny amounts of mutated mtDNA that has been carried over
  • If mitochondria, or mutated mtDNA from the mother remains in the embryo by accident, then this can still cause mitochondrial disease.