Trisomy 18

How severely affected an individual is from mosaic trisomy 18 depends on which cells in the body have the 2 copies of chromosome 18 and which have 3. If all of the heart cells have 3 copies of chromosome 18, the risks to have a heart defect may be the same. If all of the kidney cells have 2 copies of chromosome 18, the risks to have a kidney abnormality may be lower. Mosaicism is very complicated, and it is challenging to predict how a baby will be affected. Typically, children with mosaic karyotypes are less severely affected however, than children with full trisomy 18.

Some babies with Trisomy 18 will require surgery. Whether surgery is recommended may depend on the overall health of the child. Possible surgery may be needed to correct heart, kidney, or other problems.

When a pregnant woman and her family are told that their unborn baby has Trisomy 18 and then it is confirmed through an amniocentesis or other prenatal diagnostic testing, it means that they are suddenly are moved from a happy expectant place into a scary world of uncertainty, numbers, and frightening medical complications. Words such as lethal or ‘incompatible with life’ may be used. In most situations, a doctor is not telling a woman to end her pregnancy, but they will give their opinion based on their medical knowledge and past experience. However bleak the possible outcomes, the doctor, genetic counselor, and medical team should respect that as parents facing this knowledge, it is that family and that pregnant woman’s choice to continue the pregnancy until term or not. It may help to talk to friends, family, doctors and faith leaders, before making a choice based on individual circumstances. It may help to reach out to organizations such as the SOFT support organization at http://trisomy.org. If a healthcare professional does not seem to be respecting or supportive of a pregnant woman’s decisions related to their pregnancy, then it is ok to seek another care team. Before changing care teams though it is best to discuss any concerns with the current doctor and team to determine if they are unknowingly pushing towards one decision or another.

Other people with a child with Trisomy 18 can be found through online support groups.
The Chromosome 18 Registry and Research Society (http://www.chromosome18.org)
Trisomy 18 Foundation (http://www.trisomy18.org)
Chromosome Disorder Outreach (http://www.chromodisorder.org)
SOFT (Support Organization for Trisomy) (http://trisomy.org)
The Arc (http://www.thearc.org)

The following provide information about Trisomy 18:
Lucile Packard Children’s Hospital at Stanford: Trisomy 13 and Trisomy 18 (http://www.stanfordchildrens.org/en/topic/default?id=trisomy-18-and-13-90-P02419)
Minnesota Department of Health (http://www.health.state.mn.us/divs/cfh/topic/diseasesconds/trisomy18.cfm)
Texas Department of State Health Services (http://www.dshs.state.tx.us/birthdefects/risk/risk11-trisomy18.shtm)
UT Health Science Center (http://www.pediatrics.uthscsa.edu/centers/Chromosome18/)

A multidisciplinary team should care for people with Trisomy 18. People with Trisomy 18 should see a geneticist or a genetic counselor. A genetic counselor can help to further explain Trisomy 18 and answer any questions you have. A genetics professional can also help you make the appropriate next referrals. Through the National Society of Genetic Counselors (NSGC) website, you can find a genetic counselor in your area (http://nsgc.org/p/cm/ld/fid=164). Other necessary specialists will be dependent on what symptoms a child has, but some may be pediatric cardiologists, ENT specialists, neurologists, physical therapists, and surgeons.

SOFT (Support Organization for Trisomy) has gathered a list of organizations that can help parents during this time (http://trisomy.org/?page_id=5085). Northside Hospital in Atlanta, GA has H.E.A.R.T.stings Perinatal Bereavement Office that gathers a list of resources as well (http://www.northsidepnl.com/our-favorite-resources.html).

Trisomy 18 is a genetic condition that causes severe health problems and is caused by an extra number 18 chromosome. People with trisomy 18 can be affected differently, but most with complete trisomy 18 will have serious symptoms. Heart defects, brain problems and intellectual disabilities are extremely common, and the majority of affected individuals have complications in other organs as well. Most babies with trisomy 18 do not survive very long after birth or are stillborn. However, a very small number can live for some time.

When someone has three copies of chromosome 18 in all of their cells, they have complete trisomy 18. Around 95% of children with trisomy 18 have complete trisomy 18. The other 5% have mosaic trisomy 18. This means that some of their cells have 2 copies of chromosome 18, and other cells have 3 copies of trisomy 18. Almost all mosaic trisomy 18 babies begin with full trisomy 18 and then a cell and all the cells from that cell, lose one of the #18 chromosomes. This is how mosaicism occurs.

Historically, it has been a challenge for parents of children with Trisomy 18 to acquire some necessary interventions needed to extend life. This could be surgically correcting a heart defect or even resuscitating (reviving to prevent death) a child with Trisomy 18. There has been more push back to these conventions in recent years. Trisomy 18 is no longer on the American Academy of Pediatrics’ list of conditions where resuscitation is not recommended.

Main arguments for minimal intervention:

If neither parent has a chromosome rearrangement, the chance to have a second baby with trisomy 18 is thought to be low, but not impossible. If there is a suspicion of trisomy 18 in a baby, it is important to confirm this with genetic testing so the most accurate recurrence risk (the chance that the couple will have another baby with the same condition) can be provided. There is around a 1% chance to have a second child with trisomy 18 or another trisomy such as trisomy 21 or trisomy 13. The chance to have a child with trisomy 18 increases as a women ages; even though trisomy 18 is rare, it is seen more frequently in babies born to women in their late 30s and early 40s, as compared to babies born to younger women. Prenatal testing is available and is generally offered to interested parents through their healthcare providers caring for them during pregnancy. Prenatal genetic counselors can also provide individualized information about the possibility of having another pregnancy with a chromosome problem.

A high number of babies with Trisomy 18 will either not make it to delivery or will be stillborn. The chance for survival to delivery increases with gestational age. At 12 weeks gestation, a baby with Trisomy 18 has a 28% chance to make it to term. This number increases to 41% at 20 weeks gestation. It is important to remember, however, that many babies with trisomy 18 may make it to term but are stillborn.

People with trisomy 18 have an extra chromosome 18 in all of their cells. Humans generally have 46 chromosomes (23 pairs) in every cell in their body. Twenty two pairs are labelled with numbers (chromosome 1, chromosome 2, chromosome 3, etc.) and are called autosomes. The last or 23rd pair are the gender chromosomes (XX in females and XY in males). Humans generally have two copies of every chromosome, including chromosome 18. The chromosomes are comprised of genes and therefore carry our DNA. Duplicating or deleting genes can cause health problems. People with trisomy 18 have three copies of chromosome 18, and therefore have an extra set of all the genes located on this specific chromosome. Having a whole extra chromosome means there are a lot of genes with the wrong dosage (three copies instead of two copies). The extra genetic material typically leads to serious health problems.

Chromosomes are made up of genes, and genes act as the instructions for the body. Extra or missing genetic information can lead to health problems, because there are altered instructions for the cells of the body. Adding an extra complete copy of chromosome 18 can cause heart defects, intellectual disability, defects of the brain, growth problems and other health problems.

Babies with trisomy 18 are often born very small and frail. They have serious medical problems and physical defects including: overlapping fingers, clenched fists and a specific type of foot defect called ‘rocker bottom feet’. They may also have heart defects, low set ears, intellectual issues and brain problems. They usually have growth difficulties, which can be seen by ultrasound before the baby is born. Babies with trisomy 18 often have respiratory and feeding difficulties. Most pass away in utero or shortly after birth but those that survive after birth generally have severe intellectual disability.

At least 1 abnormality is found in 90% of pregnancies with Trisomy 18, and around half of babies with Trisomy 18 have two ultrasound findings. The finding could vary from inadequate growth (intrauterine growth restriction) to a heart defect. Other findings are increased nuchal translucency, decreased or absent nasal bone, choroid plexus cysts (small cysts in brain), hands held with overlapping fingers, omphalocele (opening in abdominal wall), single umbilical artery, rocker bottom feet and polyhydramnios.

Some resources that help parents capture and remember their child with Trisomy 18 include:
The Angel Pics Project (http://www.babyangelpics.com)
Casting Keepsakes (http://www.castingkeepsakes.com)
The Kendall Keepsake Foundation (http://www.kendallkeepsake.org/About.php)
Molly Bears (http://www.mollybears.com)
Now I lay me down to sleep (ttps://www.nowilaymedowntosleep.org” target=”_blank”>https://www.nowilaymedowntosleep.org” target=”_blank”>ttps://www.nowilaymedowntosleep.org)

Most often, trisomy 18 is not inherited. Trisomy 18 most often occurs because of a random mistake in the division of egg or sperm cells. However, trisomy 18 can be inherited if a parent has a rearrangement of chromosome material that involves chromosome 18. This rearrangement can also be called a “balanced translocation”. Humans generally have 46 chromosomes (23 pairs) in every cell in their body. We label them chromosome 1, chromosome 2, chromosome 3, etc. Humans generally have two copies of every chromosome, including chromosome 18. Sometimes bits of chromosomes can swap places. For example the top of one chromosome 2 and the top of one chromosome 18 switch places. The swap is called a translocation or a rearrangement. A person with that particular translocation would have a balanced translocation, because they aren’t missing any genetic information. That person’s children would have an increased chance to inherit a chromosome abnormality though, like partial trisomy 18. Analyzing a parent’s chromosomes can determine whether a parent has a balanced translocation. Balanced rearrangements are identified in about 1/1000 individuals, usually through the birth of a baby with an unbalanced chromosome condition.

There can be variable expression among children with trisomy 18. A baby with trisomy 18 will likely not have every possible symptom. Certain symptoms, like intellectual disability, are predicted to be found in most babies with trisomy 18. Degree of symptom severity may depend on how many cells in the body have three copies of chromosome 18. The term mosaicism is used if not all cells in the body have three copies of chromosome 18. Typically, only blood cells are tested to diagnosis trisomy 18. Some medical professionals believe that individuals with less severe trisomy 18 may have some cells with only 2 copies of chromosome 18 but this is hard to prove since samples of tissue from other parts of the body are not easily available to test. A sample of skin may be tested if mosaic trisomy 18 is suspected.

As of January 2016, Trisomy 18 is not on the Recommended Uniform Screen Panel (RUSP). The RUSP is created by the Health Resources and Services Administration, and states use this list to guide what conditions they screen for on newborn screening. However, testing can be done on newborns if there is a concern for trisomy 18. Trisomy 18 can be diagnosed through fluorescence in situ hybridization (FISH) testing, karyotype, or chromosomal microarray. Your healthcare provider may choose one type of test or another based off of your insurance, turnaround time, and how strong his/her suspicion is Trisomy 18.

There are a few types of genetic tests that can diagnose Trisomy 18. Trisomy 18 can be diagnosed through fluorescence in situ hybridization (FISH) testing, karyotype, or chromosomal microarray. Your healthcare provider may choose one type of test or another based off of your insurance, turnaround time, and how strong his/her suspicion is Trisomy 18.

There is research being conducted on Trisomy 18. [link url="www.ClinicalTrials.gov” target=”_blank”>ClinicalTrials.gov can provide up-to-date information on research being conducted. The Trisomy 18 Foundation has a summary page on research (http://www.trisomy18.org/resources/parents-and-families/what-does-the-medical-literature-say-about-treatments/). SOFT (Support Organization for Trisomy) provides information on research as well (http://trisomy.org/?page_id=3111).

There is no treatment that can cure Trisomy 18. However, some specific health problems faced by babies and children with Trisomy 18 do have treatments available. For example, your healthcare provider can help you find services to improve feeding ability or talk about the option of feeding through a tube directly into the stomach. Some babies with breathing difficulties may need a machine to help them receive enough oxygen as well. Surgical intervention may be an option in situations where a baby has a heart defect or other birth defect. Other supportive services and therapies, like physical therapy or individualized education plans, may be helpful to some children as well. Support organizations such as SOFT and UNIQUE have very useful websites that discuss treatments for specific health problems and day-to-day living issues that have worked for their children with Trisomy 18 or a related issue. One such page can be reached at the SOFT "Helpful Information" page at http://trisomy.org/?page_id=5089.

If a diagnosis of trisomy 18 has been confirmed through amniocentesis or CVS, some families will consider termination. This can be the right decision for some families despite possibly being very difficult. Different states will have restrictions on when a pregnancy termination procedure can be performed. A reproductive genetic counselor can help you better understand the options for your specific state.
FindLaw is an online service that describes the laws regarding abortion for different states (http://statelaws.findlaw.com/family-laws/abortion.html). This can be a useful starting point for understanding the laws in your state. It is important to note though that new laws/ restrictions can be passed so the information on this site may not be up to date.

Prenatal testing is available for trisomy 18. With prenatal diagnosis, baby DNA is tested during the pregnancy to determine whether the baby has trisomy 18. The fetal DNA sample is gathered through either an amniocentesis or chorionic villus sampling (CVS). An amniocentesis involves collecting some of the amniotic fluid surrounding the baby with a needle guided by an ultrasound. Fetal skin cells are in that fluid. A CVS involves collecting some of the placental cells, which typically are the same as the cells of the baby. A CVS procedure can be performed as early as 11 weeks of the pregnancy while an amniocentesis is generally offered after 15 weeks of the pregnancy.

Some families may like to have a diagnosis before birth to help them prepare for the delivery. Other families may make a decision about termination from prenatal diagnostic testing results. There are benefits, limitations, and risks to both of these procedures.

Preimplantation genetic diagnosis (PGD) is available for trisomy 18. PGD allows for parents to only implant embryos into the mother’s uterus that do not have trisomy 18. PGD is an option when mothers are using in vitro fertilization (IVF). A woman’s egg cells are retrieved and fertilized in a petri dish with sperm cells. After growth for 3-5 days, one cell can be biopsied, and the genetic make up can be studied. Embryos with trisomy 18 (or other chromosome problems) would not be used for implantation into the mother’s uterus, thereby minimizing the chances of having a baby affected with trisomy 18. IVF and PGD can be costly (both financially, time consuming and emotionally) but for families with infertility, these procedures can help them have healthy babies. IVF is not guaranteed to lead to pregnancy every time.

The life expectancy of an individual with trisomy 18 can vary considerably. The heart defects and breathing difficulties, and other organ abnormalities associated with trisomy 18 can make it difficult for babies to survive. Some babies with trisomy 18 will die before birth, and be born stillborn. Other times, babies live to delivery but they may pass away a few hours or days later. Around 5% to 10% of babies with trisomy 18 are able to survive through the first year. Currently, the longest anyone has lived with trisomy 18 is into their 20s.

Trisomy 18 most often occurs randomly as sperm and eggs are created, most commonly due to a process called nondisjunction. Humans generally have 46 chromosomes (23 pairs) in every cell in their body. When a woman’s eggs are made, each egg generally has one copy of each of the 23 chromosomes. The same is true for sperm. The 23 copies from the sperm and the 23 copies from the egg then combine to create a person with 46 chromosomes (23 pairs). When nondisjunction happens, an egg or a sperm is created with 2 or 0 copies of a chromosome instead of the usual 1. If an egg with two chromosome 18’s combines with a sperm with 1 chromosome 18, the baby will have trisomy 18.

There are multiple ways to help this community through financial contribution. You can donate to a support group like the Trisomy 18 Foundation (http://www.trisomy18.org) or SOFT: Support Organization for Trisomy (http://trisomy.org). Support groups will use their funds differently. Some will help to raise awareness, assist people with Trisomy 18, or donate to medical research. You can also donate to the Chromosome 18 Registry and Research Society http://www.chromosome18.org).

Through the National Society of Genetic Counselors (NSGC) website, you can find a genetic counselor in your area (http://nsgc.org/p/cm/ld/fid=164). A genetic counselor can help to further explain Trisomy 18 and answer any questions you have.

[link url="www.ClinicalTrials.gov” target=”_blank”>ClinicalTrials.gov can provide up-to-date information on research being conducted. People can choose to participate in the Chromosome 18 Registry and Research Society (http://www.chromosome18.org). SOFT (Support Organization for Trisomy) provides information on research as well (http://trisomy.org/?page_id=3111).

There are a few types of genetic tests that can diagnose Trisomy 18. Trisomy 18 can be diagnosed through fluorescence in situ hybridization (FISH) testing, karyotype, or chromosomal microarray. Your healthcare provider may choose one type of test or another based off of your insurance and how strong his/her suspicion is Trisomy 18.

About 1 in every 6000 babies born alive has trisomy 18, although the condition occurs in approximately 1 in every 2500 pregnancies. Trisomy 18 occurs more often to babies born to older women, as compared to babies born to younger mothers. In other words, trisomy 18 is related to advancing maternal age. Babies with trisomy 18 frequently do not survive to birth and are stillborn or miscarry early in the pregnancy. Trisomy 18 is seen in all populations and is not related to ethnicity.

The chance to have a child with trisomy 18 does increase as a woman ages. Overall, more babies with trisomy 18 are born to women under the age of 35, but the chance to have a child with trisomy 18 is greater in mothers who are over 35 years old. A prenatal or reproductive genetic counselor can share the specific risk for a woman considering pregnancy. The National Society of Genetic Counselors can help in locating a genetic counselor in your area, Search for a genetic counselor here

If a diagnosis of trisomy 18 has been confirmed through amniocentesis or CVS, support resources are available to help them as they carry their baby until birth. One of the best sources of support is perinatal hospice. Some areas have perinatal hospice program associated with their medical centers or nearby. One such listing can be found on Perinatal hospice. org (http://www.perinatalhospice.org/list-of-programs.html). This same website provides lists of support, parent stories, birth plans, and suggestions that can be very helpful at http://www.perinatalhospice.org/resources-for-parents.html. Specific to families whose unborn baby has been diagnosed with a Trisomy like Trisomy 18, the SOFT organizations in the United States and United Kingdom have practical suggestions, support, stories, and ideas on their websites on pages such as http://www.soft.org.uk/Help-for-Families/Decisions-During-Pregnancy/Continuing-with-your-Pregnancy. It can be very helpful to talk to another family who have been in a similar situation and carried their baby with Trisomy 18 until birth. Feel free to talk with your OB-Gyn, genetic counselor, or reach out to SOFT if you are interested in talking with another family.

Noninvasive prenatal testing (NIPT) often is available for trisomy 18. NIPT is a screening option for pregnant women. This newer blood screening test has been available since 2013. Most laboratories offering this test state that the test identifies about 98% of pregnancies affected with trisomy 18. This test evaluates pieces of placental DNA that are outside of cells and are in the mother’s blood. Parents are recommended not to make permanent decisions about the pregnancy solely based on NIPT results. Diagnostic testing like chorionic villus sampling (CVS) or amniocentesis can confirm or rule out a screen result. More research needs to be conducted to better understand and improve the accuracy of this test.

Trisomy 18 is also referred to as Edwards syndrome. Trisomy 18 is often abbreviated to T18 and can be called a chromosome condition or chromosome abnormality. Trisomy 18, along with trisomy 13 and trisomy 21, are sometimes called autosomal trisomies. Autosomes are the chromosomes that are the same between males and females. 22 of the 23 pairs of chromosomes are autosomes, including chromosome 18. Therefore, trisomy 18 can be called an autosomal trisomy. The ‘tri’ in trisomy refers to three copies of the chromosome, instead of the typical 2 copies. Chromosomes are the structures present in every cell of our body and they are responsible for carrying our DNA or genetic material.

There are good support groups for Trisomy 18.

The Chromosome 18 Registry and Research Society (http://www.chromosome18.org)
Trisomy 18 Foundation (http://www.trisomy18.org)
Chromosome Disorder Outreach (http://www.chromodisorder.org)
SOFT (Support Organization for Trisomy) (http://trisomy.org)
The Arc (http://www.thearc.org)

There are not different onsets for trisomy 18. The extra copy of chromosome 18 is present in the baby’s cells from early in prenatal development, most often conception. Some symptoms of trisomy 18 are revealed through prenatal ultrasounds or prenatal testing. Babies with complete trisomy 18 will almost always have symptoms before birth, such as growth being slower than expected while in the womb. Therefore, all babies with trisomy 18 are diagnosed either prior to birth or very early in life.

There are support groups for women who have decided to not continue a pregnancy.

A Heartbreaking Choice (http://www.aheartbreakingchoice.com)
Our Heartbreaking Choices (http://www.ohcbook.com/support-resources/online-grief-and-loss-support/)
Ending a Wanted Pregnancy (http://endingawantedpregnancy.com)

There are other diseases that look like trisomy 18. Babies with trisomy 13 may have symptoms similar to babies with trisomy 18. Genetic testing can distinguish between these two different genetic conditions. Trisomy 13 occurs when a person has three copies of trisomy 13 instead of 2. The common symptoms include a small head size(microcephaly), growth retardation or a small body size, difficulty with feeding and other abnormalities including kidney, brain and heart abnormalities.

Another disease similar to trisomy 18 is Bowen Hutterite syndrome. This condition is autosomal recessive which means an affected child inherits a genetic mutation for the condition from each of his/her parents. Microcephaly is usually present as well as growth delays, a small chin(micrognathia and rocker bottom feet.

Not all babies with trisomy 18 are born prematurely. A baby born between 37 and 42 weeks of gestation is considered full term. Around 1/3 of babies with trisomy 18 are born before 37 weeks of gestation.