Editing Genetic disorder (section)

=== Mitochondrial ===
{{Main|Mitochondrial disease|Mitochondrial DNA}}
This type of inheritance, also known as maternal inheritance, is the rarest and applies to the 13 genes encoded by [[mitochondrial DNA]]. Because only egg cells contribute mitochondria to the developing embryo, only mothers (who are affected) can pass on mitochondrial DNA conditions to their children. An example of this type of disorder is [[Leber's hereditary optic neuropathy]].<ref>{{cite book | vauthors = Shemesh A, Sood G, Margolin E | chapter = Leber Hereditary Optic Neuropathy (LHON) | title = StatPearls [Internet] | location = Treasure Island (FL) | publisher = StatPearls Publishing | chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK482499/ }}</ref>

It is important to stress that the vast majority of [[mitochondrial diseases]] (particularly when symptoms develop in early life) are actually caused by a [[nuclear gene]] defect, as the mitochondria are mostly developed by non-mitochondrial DNA. These diseases most often follow autosomal recessive inheritance.<ref>{{Cite book|title=Thompson & Thompson Genetics in Medicine| vauthors = Nussbaum R, McInnes R, Willard H |publisher=Saunders|year=2007|isbn=978-1-4160-3080-5|location=Philadelphia PA|pages=144, 145, 146}}</ref>