Edwards syndrome, also called trisomy 18, causes a wide range of serious physical and developmental symptoms that are usually visible at birth. Babies with this condition have an extra copy of chromosome 18, which disrupts normal development and affects nearly every organ system. About 90% of affected infants do not survive past their first birthday, though the severity of symptoms depends on the type of trisomy involved.
Facial and Head Features
Babies born with Edwards syndrome typically have a distinct facial appearance. The head is unusually small with a prominent back of the skull. The eye sockets are underdeveloped, the eye openings are short, and the mouth and jaw are notably small. Together, these features give the face a pinched appearance. The ears are low-set and often malformed in shape.
Hands, Feet, and Skeletal Signs
One of the most recognizable signs of Edwards syndrome is a clenched fist where the index finger overlaps the third and fourth fingers. This hand positioning is present at birth and is often one of the first features that raises concern. Clubfeet and rocker-bottom feet, where the sole of the foot is rounded rather than arched, are also common. A short breastbone and narrow pelvis are typical skeletal findings. As children grow, spinal problems like scoliosis can develop, further affecting movement and posture.
Heart and Internal Organ Problems
The most life-threatening symptoms of Edwards syndrome are internal. Heart defects are present in the vast majority of affected babies, and these malformations are a leading cause of the condition’s high mortality rate. Holes between the heart’s chambers and structural abnormalities of the heart valves are among the most frequent defects. Kidney malformations and gastrointestinal abnormalities also occur frequently. Some babies have difficulty with automatic breathing due to problems with the central nervous system, which can cause episodes where breathing temporarily stops.
Feeding difficulties are another major concern. Many babies with Edwards syndrome struggle to suck and swallow effectively, which leads to poor weight gain and increases the risk of infections.
Cognitive and Motor Development
Edwards syndrome causes severe intellectual disabilities. Among the roughly 10% of children who survive past their first birthday, most never learn to walk or talk. These children require significant, ongoing support from families and caregivers throughout their lives. Despite these challenges, families of long-term survivors describe their children as living fulfilling lives with the right care and support in place.
How Symptoms Vary by Type
Not all cases of Edwards syndrome are equally severe. There are three types, and the symptoms differ considerably between them.
Full trisomy 18 is the most common and most serious form. Every cell in the body carries the extra chromosome, and most babies with this type die before or shortly after birth. The full range of symptoms described above, from heart defects to skeletal abnormalities, is present.
Mosaic trisomy 18 is less common. In this form, only some cells have the extra chromosome while others are normal. Symptoms tend to be less severe, though they vary widely depending on how many cells are affected and where in the body those cells are. Some individuals with mosaic trisomy 18 survive into adulthood.
Partial trisomy 18 is the rarest type. Only a portion of the extra chromosome is present, and symptoms may also be less serious. Like mosaic trisomy 18, some people with partial trisomy 18 grow up to become adults.
How Edwards Syndrome Is Detected
Edwards syndrome can be suspected during pregnancy through routine screening. Ultrasound may reveal signs such as slow fetal growth, heart abnormalities, or unusual hand positioning. Blood screening tests that analyze fragments of fetal DNA in the mother’s blood can also flag an increased risk. A definitive diagnosis requires testing the baby’s chromosomes directly, either through a sample taken during pregnancy or from a blood draw after birth. This chromosome analysis confirms whether an extra copy of chromosome 18 is present and identifies which type of trisomy is involved.
When Edwards syndrome is diagnosed after birth, the combination of visible features, particularly the clenched fists, small jaw, rocker-bottom feet, and heart defects, typically prompts immediate genetic testing to confirm the diagnosis.