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i watch a lot of E.R so i always hear them saying different diseases…

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i watch a lot of E.R so i always hear them saying different diseases and things and then i research them
here are some of the ones i have researched lately.its a lot of reading but it is interesting because they aren't exactly the most popular(i had never heard of them before) diseases but they are interesting in the difference of chromosomes between the disease and our regular count of chromosomes(46 chromosomes - 23 pairs)



Trisomy 18 or Edwards Syndrome(pictures courtesy of Google Images) (named after John H. Edwards, who first described the syndrome in 1960) is a genetic disorder. It is the most common autosomal trisomy after Down Syndrome that carries to term.
Cause

It is caused by the presence of three — instead of two — copies of chromosome 18 in a fetus or infant's cells.

The additional chromosome usually occurs before conception. A healthy egg or sperm cell contains individual chromosomes - one to contribute to each of the 23 pairs of chromosomes needed to form a normal cell with 46 chromosomes. Numerical errors arise at either of the two meiotic divisions and cause the failure of segregation of a chromosome into the daughter cells (non-disjunction). This results in an extra chromosome making the haploid number 24 rather than 23. Fertilization of these eggs or sperm that contain an extra chromosome results in trisomy, or three copies of a chromosome rather than two.

Prognosis

The survival rate for Edwards Syndrome is very low. About half die in utero. Of liveborn infants, only 50% live to 2 months, and only 5–10% will survive their first year of life. Major causes of death include apnea and heart abnormalities. It is impossible to predict the exact prognosis of an Edwards Syndrome child during pregnancy or the neonatal period. As major medical interventions are routinely withheld from these children, it is also difficult to determine what the survival rate or prognosis would be for the condition if they were treated with the same aggressiveness as their genetically normal peers.

Incidence/prevalence

The rate of occurrence for Edwards Syndrome is ~ 1:3000 conceptions and 1:6000 live births, as 50% of those diagnosed prenatally with the condition will not survive the prenatal period. Although women in their 20s and 30s may conceive Edwards Syndrome babies, there is an increased risk of conceiving a child with Edwards Syndrome as a woman's age increases.

Variations

A small percentage of cases occur when only some of the body's cells have an extra copy of chromosome 18, resulting in a mixed population of cells with a differing number of chromosomes. Such cases are sometimes called mosaic Edwards syndrome. Very rarely, a piece of chromosome 18 becomes attached to another chromosome (translocated) before or after conception. Affected people have two copies of chromosome 18, plus extra material from chromosome 18 attached to another chromosome. With a translocation, the person has a partial trisomy for chromosome 18 and the abnormalities are often less than for the typical Edwards syndrome.

Features and characteristics

Symptoms and findings may be extremely variable from case to case. However, in many affected infants, the following may be found:

* Arthrogryposis a muscle disorder that causes multiple joint contractures at birth
* Growth deficiency
* Feeding difficulties
* Breathing difficulties
* Developmental delays
* Mental retardation
* Undescended testicles in males
* Prominent back portion of the head
* Small head (microcephaly)
* Low-set, malformed ears
* Abnormally small jaw (micrognathia)
* Small mouth
* Cleft lip/Cleft palate
* Upturned nose
* Narrow eyelid folds (palpebral fissures)
* Widely-spaced eyes (ocular hypertelorism)
* Drooping of the upper eyelids (ptosis)
* Overlapped, flexed fingers
* Underdeveloped or absent thumbs
* Underdeveloped nails
* Absent radius
* Webbing of the second and third toes
* Clubfeet or Rocker bottom feet
* Small pelvis with limited movements of the hips
* Short breastbone
* Kidney malformations
* Structural heart defects at birth (i.e., ventricular septal defect, atrial septal defect, patent ductus arteriosus)
* Intestines protruding outside the body (omphalocele)



Patau syndrome(pictures courtesy of Google Images), also known as trisomy 13, is a chromosomal abnormality, a syndrome in which a patient has an additional chromosome 13 due to a non-disjunction of chromosomes during meiosis. The extra chromosome 13 disrupts the normal course of development, causing the characteristic features of Patau syndrome. Like all non-disjunction diseases (Down syndrome, Edwards syndrome, etc...) the risk of disease in the offspring increases with maternal age at pregnancy. Patau syndrome affects approximately 1 in 15,000 live births.

Causes

Most cases of Patau's syndrome result from trisomy 13, which means each cell in the body has three copies of chromosome 13 instead of the usual two copies. A small percentage of cases occur when only some of the body's cells have an extra copy of chromosome 13, resulting in a mixed population of cells with a differing number of chromosomes, such cases are called mosaic Patau.

Patau syndrome can also occur when part of chromosome 13 becomes attached to another chromosome (translocated) before or at conception. Affected people have two copies of chromosome 13, plus extra material from chromosome 13 attached to another chromosome. With a translocation, the person has a partial trisomy for chromosome 13 and often the physical signs of the syndrome differ from the typical Patau syndrome.

Most cases of Patau syndrome are not inherited, but occur as random events during the formation of reproductive cells (eggs and sperm). An error in cell division called non-disjunction can result in reproductive cells with an abnormal number of chromosomes. For example, an egg or sperm cell may gain an extra copy of chromosome 13. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra chromosome 13 in each of the body's cells.

Mosaic Patau syndrome is also not inherited. It occurs as a random error during cell division early in fetal development. As a result, some of the body's cells have the usual two copies of chromosome 13, and other cells have three copies of the chromosome.

Patau syndrome due to a translocation can be inherited. An unaffected person can carry a rearrangement of genetic material between chromosome 13 and another chromosome. This rearrangement is called a balanced translocation because there is no extra material from chromosome 13. Although they do not have signs of Patau syndrome, people who carry this type of balanced translocation are at an increased risk of having children with the condition.

Prognosis

Most embryos with trisomy 13 do not survive gestation and are spontaneously aborted. Of those surviving to term gestation, approximately 82-85% do not survive past 1 month of age, and 85% do not survive past 1 year of age.[1] Certain malformations, especially holoprosencephaly and other central nervous system malformations, yield a more grave prognosis. Of those infants that survive past 1 year, most have few major malformations, but the prognosis remains poor, owing to multiple factors including long term neurological disability, feeding difficulty, and frequent pneumonia and other respiratory infections. Presently over 75 stories of Living Trisomy 13 - Patau Syndrome children from all over the world. See [1].[citation needed]

Manifestations and physical findings

Of those embryos that do survive to gestation and subsequent birth, common anomalies include:

* mental & motor retardation
* polydactyly (extra digits)
* microcephaly
* low-set ears
* holoprosencephaly (failure of the forebrain to divide properly).
* heart defects
* structural eye defects, including microphthalmia, Peters anomaly, cataract, iris and/or fundus (coloboma), retinal dysplasia or retinal detachment, sensory nystagmus, cortical visual loss, and optic nerve hypoplasia
* cleft palate or hare lip
* meningomyelocele (a spinal defect)
* omphalocele (abdominal defect)
* abnormal genitalia
* abnormal palm pattern
* overlapping of fingers over thumb.

Recurrence risk

Unless one of the parents are carriers of a translocation the chances of a couple having another trisomy 13 affected child is less than 1% (less than that of Down Syndrome).

History

Trisomy 13 was first observed by Erasmus Bartholin in 1657,[2] but the chromosomal nature of the disease was ascertained by Dr.Klaus Patau in 1960.[3] The disease is named in his honor. Patau syndrome was also described in Pacific island tribes. These reports were thought to have been caused by radiation from atomic bomb tests. The tribes were temporarily moved before and during the test by an x amount of distance. They were then put back where they had been taken; all of this occurred before it was known how long, or even if, radiation still lingered on after a nuclear explosion.


all sources are wikipedia
http://en.wikipedia.org/wiki/List_of_diseases
there is a link for you to learn a lot about diseases
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On January 31st, 2008 07:20 pm (UTC), (Anonymous) commented:
Trisomy 13
So interesting, they talked about trisomy 18 and or 13 on ER...curious as to how they handled the situation.

Here are some Wonderful support sites for both trisomy 13 and 18 are
http://www.trisomy.org
http://www.trisomyonline.org
http://www.livingwithtrisomy13.org
http://www.livingwithtrisomy.org
http://www.hopefortrisomy13and18.org
and many support resources off these links

Hope this helps,
Blessings,
ThereseAnn mom to Natalia full/trisomy13 7 yrs.
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