What is Down syndrome and trisomy 18?
Down syndrome and trisomy 18 are chromosome abnormalities. Chromosomes are the inherited structures found in all our body’s cells. They carry our genes, which are the instructions that our bodies use to grow and develop properly. We usually have 46 chromosomes, which come in 23 pairs. Generally, we get one of each pair from our mothers and the other from our fathers. Children with Down syndrome and trisomy 18 get an extra chromosome, so they have a total of 47. People with Down syndrome have mental retardation, generally in the mild to moderate range. They may also have heart defects and facial features that are characteristic of the condition. Trisomy 18 is much more severe than Down syndrome. Babies with trisomy 18 have profound mental retardation and multiple birth defects. Most babies with trisomy 18 die by their first birthday, with many not surviving the newborn period. Trisomy 18 is more rare than Down syndrome.
Related Questions
- Are women who screen positive for Down syndrome, trisomy 18, or ONTDs in a previous pregnancy eligible for an amniocentesis in their current pregnancy?
- Do the results of prenatal screening provide information other than risk for Down syndrome, trisomy 18 and open neural tube defects?
- Do the results of serum screening provide information other than risk for Down syndrome, trisomy 18 and open neural tube defects?
