Mitochondrial donation

From Wikipedia, the free encyclopedia
  (Redirected from Three-parent baby)
Jump to: navigation, search

Mitochondrial donation is a specialized form of in vitro fertilization in which the future baby's mitochondrial DNA comes from a third party. Two of several possible techniques are cytoplasmic transfer and spindle transfer. Such treatment may result in human offspring with three genetic parents, the so-called three-parent babies.[1][2][3] The procedure is intended to prevent mitochondrial diseases including diabetes mellitus and deafness and some heart and liver conditions.[4] It is the subject of considerable controversy in the field of bioethics. The procedure is not currently approved for general use in any country aside from the United Kingdom, which legalised it in 2015.[5][6]

Case of Alana Saarinen[edit]

Alana Saarinen (born 2000) is a girl from the US conceived through an infertility treatment known as cytoplasmic transfer and has DNA from three biological parents. She is the daughter of Sharon and Paul Saarinen, and a third donor. (However, the first person born using cytoplasmic transfer was Emma Ott of Pennsylvania in 1997.)

Before Saarinen's birth, her parents had gone through four attempts to have a baby through numerous IVF procedures without success. The fifth attempt using cytoplasmic transfer succeeded. The treatment involved the transfer of a third donor's cytoplasm, containing healthy mitochondria, to Sharon Saarinen's egg with unhealthy mitochondria. The egg was then fertilized with Paul Saarinen's sperm. During the process of transferring DNA, some DNA from the donor was in the embryo. Ninety-nine percent of Saarinen's genetic material is from her parents, and one percent is from the third donor.[7]

According to her mother, Saarinen is healthy and has a fairly normal life as a teenager such as playing golf and the piano, listening to music and hanging out with friends. Despite the success of Saarinen's case, cytoplasmic transfer technique was banned by the US Food and Drug Administration (in 2001) due to safety and ethical concerns. As the result of the pioneering infertility treatment, several research teams in the United Kingdom are currently[when?] requesting a regulatory approval for a similar technique called mitochondrial replacement. The technique would use a donor's healthy mitochondria to treat women at risk of passing on mitochondrial diseases to their children.[8]

Availability[edit]

The process, still in the research stage, is currently not approved as safe and effective in the United States. China prohibited it after a woman tried to undergo the procedure.[9][dead link][10] Some research is also taking place in the United States. The United Kingdom[4] became the first country to legalize the procedure after the Parliament approved The Human Fertilisation and Embryology (Mitochondrial Donation) Regulations[11] in February 2015, to come into force in October 2015.[12][13]

Technique[edit]

The process of producing a three-parent baby, Three Parent In Vitro Fertilization (TPIVF), involves taking the nucleus of one egg and inserting it into the cytoplasm of another egg which has had its nucleus removed, but still contains mitochondrial DNA, and then fertilizing the hybrid egg with a sperm. The purpose of the procedure is to remove a nucleus from a cell with defective mitochondria and place it in a donor cell with healthy mitochondria, which after fertilization will contain a nucleus with genetic material from only the two parents.[9] There is more than one method of TPIVF. The two main methods are pronuclear transfer and spindle transfer; Spindle transfer is a process where the spindle of chromosomes taken from the mother’s egg are placed into the donor egg and pronuclear transfer is the process described at the beginning of this paragraph.[14]

Although the donor egg is said to contribute only 1% to the genetic make up of the child, when examining the genetic material of these children there are still three identifiable genetic parents.[15] This is due to the fact that the donor egg usually comes from a non-maternal relative. For a child having undergone this procedure to have only two identifiable genetic parents, the donor egg must have come from a maternal relative (this is because mitochondrial DNA mtDNA is inherited maternally; thus maternal relatives will have identical mitochondrial DNA, barring random mutations). Maternal relative egg donation is not commonly used, because if the female egg has a mitochondrial disease then it is highly likely that the maternal relatives inherited the disease as well.

Ethics[edit]

Despite the promising outcomes of the two techniques, pronuclear transfer and spindle transfer, mitochondrial gene replacement raises ethical and social concerns.

According to Darnovsky, an executive director of the Center for Genetics and Society, the technique procedures would involve modification of the germline, and modifications would pass on to subsequent generations.[16] Using human embryos in vitro research is controversial because embryos are created specifically for research and the financial compensation of egg donors.[17]

Implications for identity is another ethical concern that has psychological and emotional impacts on a child's life regarding of a person's sense of identity. It debates whether the genetic make-up of children born as a result of mitochondrial replacement affect their emotional well-being when they are aware that they are different from other healthy children conceived from two parents.[18] Safety and efficacy of mitochondrial DNA replacement are still unanswered.[19]

Opponents argue that scientists are "playing God" and that children with three genetic parents may suffer both psychological and physical damage.[20] These critics include Alison Cook of Great Britain's Human Fertilisation and Embryology Authority, who argues that bans were "written to protect the welfare of the embryo and the child."[9]

On the other hand, New York University researcher James Grifo, a critic of the American ban, has argued that society "would never have made the advances in treating infertility that we have if these bans had been imposed 10 years" earlier.[9]

See also[edit]

References[edit]

  1. ^ Keim, Brandon, Three-Parent Children: Reality or Technicality?, Feb 5, 2008.
  2. ^ Alleyne, Richard.'Three parent babies' take a step closer to reality, The Telegraph, Nov. 12, 2009.
  3. ^ Randerson, James. Scientists seek to create 'three-parent' babies The New Scientist Oct. 19. 2004
  4. ^ a b Three-Parent IVF Set to Go Ahead in Britain, Discover Magazine, June 28, 2013
  5. ^ "UK approves three-person babies". BBC News (BBC). 24 February 2015. Retrieved 24 February 2015. 
  6. ^ "Britain votes to allow world's first 'three-parent' IVF babies". Reuters. 3 February 2015. Retrieved 3 February 2015. 
  7. ^ "CNN.com - How far will couples go to conceive? - Mar 12, 2004". 
  8. ^ "BBC News - The girl with three biological parents". BBC News. 
  9. ^ a b c d Frith, Maxine. Ban on scientists trying to create three-parent baby, The Independent, October 14, 2003
  10. ^ "Now, a three-parent baby". Rediff. 14 October 2003. 
  11. ^ The Human Fertilisation and Embryology (Mitochondrial Donation) Regulations 2015 No. 572
  12. ^ Knapton, Sarah (25 February 2015) "Three-Parent babies by next year after Lords change the law", The Daily Telegraph, Page 2; A similar article is available on Internet at [1], Retrieved 27 February 2015
  13. ^ Gallagher, James (3 February 2015) MPs say yes to three-person babies BBC News health, Retrieved 3 February 2015
  14. ^ "Background: Maternal spindle transfer". Retrieved 22 April 2014. 
  15. ^ Françoise Baylis (2013) The ethics of creating children with three genetic parents, Reproductive BioMedicine Online, 26(6): 531-534
  16. ^ Darnovsky, M. (2013). A slippery slope to human germline modification. Nature, 499(7457), 127
  17. ^ Amato, P., Tachibana, M., Sparman, M., & Mitalipov, S. (2014). Three-parent in vitro fertilization: Gene replacement for the prevention of inherited mitochondrial diseases. Fertility and Sterility, 101(1), 31-35.
  18. ^ "CGS : 3-Person IVF". 
  19. ^ http://ac.els-cdn.com/S1043276013001550/1-s2.0-S1043276013001550-main.pdf?_tid=057e4a48-5ae5-11e4-a0e4-00000aab0f6b&acdnat=1414090221_f91d28a4c4ca11ede355aca9305a4797
  20. ^ Check E (November 2005). "Gene study raises fears for three-parent babies". Nature 438 (7064): 12. doi:10.1038/438012a. PMID 16267521. 

External links[edit]