Generally NIPS will include screening for a few common chromosome conditions, with the option of adding more detailed analyses for more rare conditions. You and your healthcare provider should decide what conditions you’ll be screened for.
Typically, a cell contains 46 total chromosomes, organized into 23 pairs. A trisomy occurs when the cells of the body contain an extra chromosome (three instead of two) in one of these pairs. The impact of a trisomy can vary depending on which chromosome is affected. The most common trisomies affect chromosomes 21, 18 and 13. These are the conditions always included in NIPS.
Individuals with Down syndrome have an IQ that typically ranges from mild to moderate intellectual disability. Health conditions can include low muscle tone, heart defects, intestinal issues and vision or hearing conditions. While the average life expectancy for a person with Down syndrome is 60 years, health conditions like those mentioned above may result in a shorter life expectancy.
Each person with Down syndrome is unique and the severity of the symptoms varies greatly among individuals. Outcomes for people with Down syndrome have improved significantly in the past 40 years with increased access to education, social supports, employment opportunities, and family support.
In individuals with trisomy 18, health problems are often life-threatening, including heart defects and breathing difficulties. Birth defects can occur in other organ systems as well, including the kidneys and the intestines. Miscarriages are common with affected pregnancies. The majority of babies with trisomy 18 do not survive past the first year of life. Children with trisomy 18 that survive have severe intellectual disability.
Individuals with trisomy 13 often have significant birth defects and severe intellectual disability. Infants have a pattern of physical features that includes small heads and eye abnormalities, cleft lip and/or cleft palate and congenital heart defects. Median survival is 7-10 days and 90% do not survive the first year of life.
The sex chromosomes determine whether the baby will be male (XY) or female (XX). Sometimes there may be too many or too few sex chromosomes, resulting in potential health issues. Sex chromosome abnormalities are not always included in NIPS. However if they are, you can also learn the sex of the baby.
Some common sex chromosome conditions are:
- Monosomy X
- Trisomy X
- XXY (Klinefelter syndrome)
- XYY Syndrome (Jacobs syndrome)
A microdeletion occurs when a tiny piece of a chromosome is missing, or deleted. This deletion can result in birth defects or intellectual disability. Microdeletions are rare and are usually not included in NIPS.
Some common microdeletion syndromes are:
- 15q11.2 Deletion
- 1p36 Deletion Syndrome
- 22q11.2 Deletion Syndrome
- 4p Deletion
- 5p Deletion