Anencephaly
Anencephaly | |
---|---|
Illustration of an anencephalic fetus | |
Specialty | Medical genetics; pediatrics |
Symptoms | Absence of the cerebrum and cerebellum |
Risk factors | Folic acid deficiency |
Prevention | Mother taking enough folic acid |
Prognosis | Death typically occurs within hours to days after birth. |
Frequency | 1 in 4600 in the U.S. |
Anencephaly is the absence of a major portion of the
Signs and symptoms
The National Institute of Neurological Disorders and Stroke (NINDS) describes the presentation of this condition as follows: "A baby born with anencephaly is usually blind, deaf, unaware of its surroundings and unable to feel pain. Although some individuals with anencephaly may be born with a main brain stem, the lack of a functioning cerebrum permanently rules out the possibility of ever gaining awareness of their surroundings. Reflex actions such as breathing and responses to sound or touch may occur."[4]
Causes
Neural tube defects can follow patterns of heredity, with direct evidence of autosomal recessive inheritance.[9] As reported by Bruno Reversade and colleagues, the homozygous inactivation of the NUAK2 kinase leads to anencephaly in humans.[10] Animal models indicate a possible association with deficiencies of the transcription factor TEAD2.[11] A woman who has had one child with a neural tube defect such as anencephaly has about a 3% risk of having another child with a neural tube defect,[12] as opposed to the background rate of 0.1% occurrence in the population at large.[13] Genetic counseling is usually offered to women at a higher risk of having a child with a neural tube defect to discuss available testing.[14]
It is known that people taking certain anticonvulsants and people with insulin-dependent diabetes have a higher risk of having a child with a neural tube defect.[15]
Relation to genetic ciliopathy
Until recently, medical literature did not indicate a connection among many
Diagnosis
Anencephaly can often be diagnosed before birth through an
Meroanencephaly
Meroanencephaly is a rare form of anencephaly characterized by malformed
Holoanencephaly
The most common type of anencephaly, where the brain has entirely failed to form, except for the brain stem. Infants rarely survive more than one day after birth with holoanencephaly.[19]
Craniorachischisis
The most severe type of anencephaly where area cerebrovasculosa and area medullovasculosa fill both cranial defects and the
Prognosis
There is no cure or standard treatment for anencephaly. Prognosis is extremely poor, as many anencephalic fetuses do not survive birth and infants that are not
Epidemiology
In the United States, anencephaly occurs in about 1 out of every 4600 births.[22] Rates may be higher among Africans with rates in Nigeria estimated at 3 per 10,000 in 1990 while rates in Ghana estimated at 8 per 10,000 in 1992.[23] As of 2005, rates in China were estimated at 5 per 10,000.[23]
A high anencephaly rate of 19.7 per 10,000 live births was found in 1990/1991 in Brownsville, Texas. A cluster of cases made national headlines
Research has suggested that, overall, female babies are more likely to be affected by the disorder.[27]
Ethical issues
Organ donation
One issue concerning anencephalic newborns is
Within the medical community, the main ethical issues with organ donation are a misdiagnosis of anencephaly, the slippery slope argument, that anencephalic neonates would rarely be a source of organs, and that it would undermine confidence in organ transplantation.[29] Slippery slope concerns are a major issue in personhood debates, across the board. In regards to anencephaly, those who oppose organ donation argue that it could open the door for involuntary organ donors such as an elderly person with severe dementia. Another point of contention is the number of children who would actually benefit. There are discrepancies in statistics; however, it is known that most anencephalic children are stillborn.[29]
Proposals have been made to bypass the legal and ethical issues surrounding organ donation. These include waiting for death to occur before procuring organs, expanding the definition of death, creating a special legal category for anencephalic infants, and defining them as non-persons.[30]
In the
Brain death
There are four different concepts used to determine
Neocortical death, similar to a
Pregnancy termination
Anencephaly can be diagnosed before delivery with a high degree of accuracy. Although anencephaly is a fatal condition, the option of abortion is dependent on the abortion laws in the state.[34] According to a 2013 report, 26% of the world's population reside in a country where abortion is generally prohibited.[34][35] In 2012, Brazil extended the right of abortion to mothers with anencephalic fetuses. This decision is, however, receiving much disapproval by several religious groups.[36]
Legal proceedings
The case of baby Theresa was the beginning of the ethical debate over anencephalic infant organ donation.[28] The story of baby Theresa remains a focus of basic moral philosophy. Baby Theresa was born with anencephaly in 1992. Her parents, knowing that their child was going to die, requested that her organs be given for transplantation. Although her physicians agreed, Florida law prohibited the infant's organs from being removed while she was still alive. By the time she died nine days after birth, her organs had deteriorated past the point of being viable.[37]
United States uniform acts
The Uniform Determination of Death Act (UDDA) is a model bill, adopted by many US states, stating that an individual who has sustained either 1) irreversible cessation of circulatory and respiratory functions or 2) irreversible cessation of all functions of the entire brain, including the brain stem, is dead. This bill was a result of much debate over the definition of death and is applicable to the debate over anencephaly. A related bill, the Uniform Anatomical Gift Act (UAGA), grants individuals and, after death, their family members the right to decide whether or not to donate organs. Because it is against the law for any person to pay money for an organ, the person in need of an organ transplant must rely on a volunteer.[34]
There have been two state bills that proposed to change current laws regarding death and organ donation. California Senate Bill 2018 proposed to amend the UDDA to define anencephalic infants as already dead, while New Jersey Assembly Bill 3367 proposed to allow anencephalic infants to be organ sources even if they are not dead.[34][38]
Research
Some genetic research has been conducted to determine the causes of anencephaly. It has been found that
See also
References
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- ^ a b c d "Anencephaly Information Page: National Institute of Neurological Disorders and Stroke (NINDS)". Archived from the original on 2 December 2016. Retrieved 2016-12-02.
- ^ "Baby Without A Brain, Nickolas Coke, Update". Archived from the original on 2012-09-14.
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- ^ "Lancet 1991; 338:8760:131-137". www.sjsu.edu. Archived from the original on 2018-04-08. Retrieved 2018-12-10.
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- ^ "Neural Tube Defects (NTD)". Archived from the original on 2011-03-04. Retrieved 2011-04-01.[full citation needed]
- ^ "Anencephaly | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program". rarediseases.info.nih.gov. Archived from the original on 20 January 2022. Retrieved 4 December 2021.
- ^ "Anencephaly". Genetics Home Reference. National Institutes of Health. 22 August 2011. Archived from the original on 2011-08-05. Retrieved 28 August 2011.
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- ^ ISBN 9780199775149. Archivedfrom the original on 2016-01-31. Retrieved 2015-08-09.
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- ^ [1] Archived 2018-05-28 at the Wayback Machine. BBC News. Retrieved on 2015-04-23.
- ^ "Archived copy" (PDF). Archived (PDF) from the original on 2013-10-15. Retrieved 2013-10-15.
{{cite web}}
: CS1 maint: archived copy as title (link) - ^ Beresford, H. Richard (July 1996). "Ethics in Neuroscience: Mind over Matter" (PDF). Indiana University. Archived from the original (PDF) on November 1, 2005.
- ^ a b c d Meinke, Sue (June 1989). "Anencephalic Infants as Potential Organ Sources: Ethical and Legal Issues" (PDF). National Reference Center for Bioethics Literature. Archived (PDF) from the original on 2012-05-22. Retrieved 19 July 2012.
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(help) - ^ "The World's Abortion Laws Map 2013 Update" (PDF). Archived (PDF) from the original on 2015-12-02. Retrieved 2015-11-30.
- ^ "Anencephaly in Brazil: A New Decision, Old Issues". Archived from the original on 13 May 2012. Retrieved 19 July 2012.
- ^ Rachels, James. "What is Morality" (PDF). Archived (PDF) from the original on 2014-12-14. Retrieved 19 July 2012.
- ^ "Uniform Declaration of Death Act (UDDA)". Archived from the original on 2013-09-06. Retrieved 2013-08-23.
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