Trisomy 18

What Trisomy 18 Means

Trisomy 18, also known as Edwards syndrome, is a genetic condition caused by having an extra copy of chromosome 18 in some or all of the body's cells. Normally, people have two copies of each chromosome, but in this condition, there are three copies of chromosome 18. This extra genetic material affects how the body develops before birth.

Babies with Trisomy 18 often have low birth weight and several physical differences. These can include a small, abnormally shaped head; a small jaw and mouth; clenched fists with overlapping fingers; and defects in the heart, lungs, kidneys, intestines, and stomach. Many babies with this condition die before birth or within the first month of life, but some children live for several years with supportive care.

Why Trisomy 18 Matters in Cancer Care

While Trisomy 18 itself is not cancer, it increases the risk of certain types of cancer, especially in children. Two cancers linked to this condition are hepatoblastoma, a rare liver cancer, and Wilms tumor, a type of kidney cancer. Knowing about this increased risk helps doctors monitor children with Trisomy 18 more closely for signs of these cancers and plan appropriate care.

What Patients and Caregivers Might See or Hear

You might encounter the terms Trisomy 18 or Edwards syndrome in medical reports, genetic testing results, or discussions with your healthcare team. Because both names refer to the same condition, it’s helpful to recognize that they mean the same thing. You may also hear about the physical features or health challenges associated with the syndrome, including the increased cancer risk.

Common Confusions and How to Understand the Term

Trisomy 18 is sometimes confused with other trisomy conditions, like Down syndrome (Trisomy 21). Each trisomy affects different chromosomes and causes different health issues. It’s important not to assume that Trisomy 18 means a cancer diagnosis or that every person with the syndrome will develop cancer. Instead, it signals a higher risk that doctors will watch for.

How to Use This Information

If you see Trisomy 18 or Edwards syndrome mentioned in medical records or reports, the best step is to ask your healthcare team what it means for your or your child’s care. They can explain how it relates to diagnosis, treatment, or monitoring plans. Because this condition affects many parts of the body and can increase cancer risk, your care team may recommend specific tests or follow-up visits.

Safety and Next Steps

This information is educational and does not replace medical advice. Trisomy 18 is a complex condition, and its impact varies from person to person. Working closely with your healthcare providers is key to understanding what it means for your health and what steps to take next. Asking questions and sharing concerns helps ensure the best care for you or your child.