How is edwards syndrome transmitted

In these people, the condition is called mosaic trisomy The severity of mosaic trisomy 18 depends on the type and number of cells that have the extra chromosome. The development of individuals with this form of trisomy 18 may range from normal to severely affected. Very rarely, part of the long q arm of chromosome 18 becomes attached translocated to another chromosome during the formation of reproductive cells eggs and sperm or very early in embryonic development.

Affected individuals have two copies of chromosome 18, plus the extra material from chromosome 18 attached to another chromosome. People with this genetic change are said to have partial trisomy If only part of the q arm is present in three copies, the physical signs of partial trisomy 18 may be less severe than those typically seen in trisomy If the entire q arm is present in three copies, individuals may be as severely affected as if they had three full copies of chromosome Most cases of trisomy 18 are not inherited, but occur as random events during the formation of eggs and sperm.

An error in cell division called nondisjunction results in a reproductive cell with an abnormal number of chromosomes. For example, an egg or sperm cell may gain an extra copy of chromosome If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra chromosome 18 in each of the body's cells.

Mosaic trisomy 18 is also not inherited. It occurs as a random event during cell division early in embryonic development. As a result, some of the body's cells have the usual two copies of chromosome 18, and other cells have three copies of this chromosome. Partial trisomy 18 can be inherited. An unaffected person can carry a rearrangement of genetic material between chromosome 18 and another chromosome.

The symptoms, and how seriously your baby is affected, usually depend on whether they have full, mosaic, or partial Edwards' syndrome. Most babies with Edwards' syndrome have an extra chromosome 18 present in all cells. This is called full Edwards' syndrome. The effects of full Edward's syndrome are often more severe. Sadly, most babies with this form will die before they are born. A small number of babies with Edwards' syndrome about 1 in 20 have an extra chromosome 18 in just some cells.

This is called mosaic Edwards' syndrome or sometimes mosaic trisomy This can lead to milder effects of the condition, depending on the number and type of cells that have the extra chromosome. Most babies with this type of Edward's syndrome who are born alive will live for at least a year, and they may live to adulthood. A very small number of babies with Edwards' syndrome about 1 in have only a section of the extra chromosome 18 in their cells, rather than a whole extra chromosome This is called partial Edwards' syndrome or sometimes partial trisomy How partial Edwards' syndrome affects a baby depends on which part of chromosome 18 is present in their cells.

Edwards' syndrome is associated with certain physical features and health problems. Every baby is unique and will have different health problems and needs. They will usually have a low birthweight and may also have a wide range of physical symptoms. They may also have heart, respiratory, kidney or gastrointestinal conditions. Despite their complex needs, children with Edwards' syndrome can slowly start to do more things. If you're pregnant, you'll be offered screening for Edwards' syndrome between 10 and 14 weeks of pregnancy.

This looks at the chance of your baby having the condition. This screening test is called the combined test and it works out the chance of a baby having Edwards' syndrome, Down's syndrome and Patau's syndrome. Sometimes the possibility of Edwards syndrome is raised after the 11 to week tests usually a pregnancy ultrasound and blood test.

It is also possible to screen for Edwards syndrome through non-invasive prenatal testing NIPT , which is a blood test taken from 10 weeks of pregnancy.

But the only definite way to diagnose Edwards syndrome is through genetic testing. This can be done while the baby is in the womb using chorionic villus sampling CVS or amniocentesis.

Both these tests have a risk of miscarriage. You can talk to your obstetrician or midwife about this. Sometimes, Edwards syndrome is not suspected during pregnancy, and is only discovered when the baby is born. Visit Pregnancy, Birth and Baby website for more information on prenatal screening. There is no effective long-term treatment for babies with Edwards syndrome. Parents in this situation face a very hard choice. They can choose to try to keep their babies alive in the neonatal intensive care unit.

Or they can choose to have their baby receive palliative care until he or she dies. Visit our genetic disorders guide to learn more about genes, types of genetic disorders and where to go for help and more information. These choices will be signaled globally to our partners and will not affect browsing data. We and our partners process data to: Actively scan device characteristics for identification.

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