How can trisomy 18 be detected

Trisomy 18 and What are trisomy 18 and trisomy 13? Trisomy 18 occurs in about one out of every 6, to 8, live births and trisomy 13 occurs in about one out of every 8, to 12, live births. It's characterized by severe mental retardation and health problems involving nearly every organ system of the body. Babies with the disorders usually die by age 1, but there have been a few cases in which children survive into their teens.

Trisomy 18 is also called "Edwards syndrome" and trisomy 13 is also called "Patau syndrome" after the physicians who first described the disorders. What causes trisomy 18 and trisomy 13? When this cell contributes the extra chromosome 18 to the embryo, trisomy 18 results. When this cell contributes the extra chromosome 13 to the embryo, trisomy 13 results. What types of problems do children with trisomy 18 and trisomy 13 typically have?

Trisomy 18 thin and frail babies with a weak cry feeding problems small head size with the back of the head prominent ears are usually low-set on the head mouth and jaw unusually small shortened sternum breastbone about 90 percent of babies have heart defects clenched fists difficulty extending fingers contracted joints spina bifida , eye problems, cleft lip and palate , and hearing loss may be present seizures high blood pressure and kidney problems scoliosis curvature of the spine in males, the testes fail to descend into the scrotum.

This is checked in a lab to find the extra chromosome. It will also depend on how severe the condition is. Severe, often life-threatening health problems occur in both trisomy 13 and trisomy Treatment for complications varies depending on the body organ affected and the severity of the problem. There is no reason to believe a parent can do anything to cause or prevent trisomy 13 or 18 in their child.

If you are younger than 35, the risk of having a baby with trisomy 13 or 18 goes up slightly each year as you get older. After a baby is born with suspected trisomy 13 or 18, a healthcare provider will take a blood sample to do a chromosome analysis karyotype.

This confirms trisomy 13 or This test also shows the chromosome problem that caused the disorder. This information is important in assessing the risk in future pregnancies. Translocation and mosaic trisomy 13 and 18 have different risks for future pregnancies. Your healthcare provider may refer you to a genetic counselor.

This expert can explain the results of chromosome tests in detail. They can talk about risks for future pregnancies. The counselor can tell you what tests are available to diagnose chromosome problems before a baby is born. A diagnosis of trisomy 13 or trisomy 18 can be overwhelming and upsetting. You will face difficult decisions about how to care for your baby. Many babies born with trisomy 13 or trisomy 18 may not live beyond the first few days or weeks of life.

So you may have to cope with your baby never coming home from the hospital. Many resources are available to help you. These include early intervention services, hospice care, social workers, a hospital chaplain or clergy, and genetic counselors.

Support groups that include other families dealing with a similar problem can also help you cope with questions and emotions. The extra genetic material disrupts the normal course of development, causing the characteristic features of trisomy Approximately 5 percent of people with trisomy 18 have an extra copy of chromosome 18 in only some of the body's cells. 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. If it's not possible to measure the fluid at the back of your baby's neck, or you're more than 14 weeks pregnant, you'll be offered screening for Edwards' syndrome as part of your week scan. This is sometimes known as the mid-pregnancy scan. It's an ultrasound scan that looks at how your baby is growing.

Screening cannot identify which form of Edwards' syndrome your baby may have, or how it will affect them. If the combined test shows that you have a higher chance of having a baby with Edwards' syndrome, you'll be offered a test to find out for certain if your baby has the condition. This diagnostic test involves analysing a sample of your baby's cells to check if they have an extra copy of chromosome These are invasive tests that increase your chance of having a miscarriage.

Your doctor will discuss this with you. A specialist doctor obstetrician or midwife will explain what the screening results mean and talk to you about your options. This is a very difficult situation and it's normal to feel a whole range of emotions. It may help to talk to your doctor, family and friends, or partner about what you're thinking and how you're feeling. If you're told your baby has Edwards' syndrome, either before birth or afterwards, you'll be offered support and information.

You can visit the SOFT UK website for support and more information on Edwards' syndrome, and to contact other families affected by the condition. You can also contact Antenatal Results and Choices ARC , which has information about screening tests and how you might feel if you're told your baby does have, or might have, a problem. ARC has a helpline that can be reached on , or from a mobile, Monday to Friday, 10am to 5.

The helpline is answered by trained staff, who can offer information and support. Read more about what happens if antenatal screening tests find something. If doctors believe your baby has Edwards' syndrome after they're born, a blood sample will be taken to see if there are extra copies of chromosome Treatment will focus on the symptoms of the condition, such as heart conditions, breathing difficulties and infections.

Your baby may also need to be fed through a feeding tube, as they can often have difficulty feeding.