Williams Syndrome Diagnosis

How Is Williams Syndrome Diagnosed?

How Is Williams Syndrome Diagnosed?

Williams syndrome is a rare genetic condition that affects cognitive development and facial appearance. Individuals with Williams syndrome are known to have a unique personality that is extremely friendly with a high level of empathy and anxiety. This neurodevelopmental condition has recognizable physical characteristics, such as very full cheeks, large ears, prominent lips, a small jaw, and an upturned nose. Individuals with Williams syndrome may deal with developmental delays when it comes to achieving certain milestones, such as speaking, walking, or a delay in socializing with their peers. Individuals with Williams syndrome are usually very friendly and may have difficulty identifying strangers. Williams syndrome ranges in severity and not all individuals will experience the same set of signs and symptoms. The varying severity and range of symptoms may make Williams syndrome difficult for parents to recognize, though there are a number of tests doctors will perform if a baby or child is suspected to have Williams syndrome. The Special Olympics team is breaking down these tests and the timeline for when Williams syndrome is usually diagnosed in individuals.

Diagnosing Williams Syndrome

Diagnosing Williams syndrome can involve a number of tests to ensure a proper diagnosis can be confirmed and a treatment plan can be developed. A team of physicians may work with you and your child to conduct these tests and take into account a number of different factors when confirming a diagnosis. The tests may include:

Physical Exam

Doctors will generally begin by conducting a thorough physical exam to observe the features of the condition. Physical symptoms of Williams syndrome include low muscle tone, which can affect the development of your child and cause difficulties with sitting up, rolling over, or walking, and small stature. Individuals with Williams syndrome often have recognizable facial features, especially full cheeks, large eyes with a vertical skin fold that covers the inner corner of the eye, prominent lips, and a small jaw. They may have larger ears and a wide mouth. Individuals with Williams syndrome may experience hearing loss or farsightedness and may have scoliosis or an unsteady gait. A physical exam allows doctors to closely examine these common physical symptoms and determine the severity of symptoms and developmental delays.


An echocardiogram is an ultrasound test that checks the structure and function of the heart and blood vessels. This test created a graphic outline of the heart’s movement through the use of an ultrasound, which uses high-frequency sound waves to take pictures of the heart’s valves, chambers, and blood vessels. Echocardiograms can be used during the diagnosis of Williams syndrome to determine the severity, since one of the more serious symptoms of Williams syndrome is cardiovascular disease. Individuals with Williams commonly experience narrowing of the blood vessels during formation in utero, which can lead to increased blood pressure, arrhythmia, and cardiac failure. Examining these blood vessels will help doctors determine if your baby or child has narrowed blood vessels and their severity, if they do.


An EKG, or electrocardiogram, is a test that is used to record the electrical signals in the heart. It is a common and painless test that can be used to detect heart problems and monitor heart health. This test will be completed in a health care provider’s office, a clinic, or a hospital. An EKG can be used to detect irregular heart rhythms, or arrhythmias, or to detect if blood vessels are narrowed around the heart, which is a symptom of Williams syndrome.

DNA Testing

While evaluation for a Williams syndrome diagnosis will include observing the physical symptoms, such as heart defects and facial abnormalities, to confirm a Williams syndrome diagnosis, most doctors will conduct DNA testing. A DNA test will be used to check for missing genes, since Williams syndrome is caused by 26–28 missing genes in a small region of one of the child’s chromosomes. There are two types of DNA tests that are commonly used to diagnose this condition, both of which involve analyzing a small amount of blood that will need to be drawn from your child.
<h3?FISH Test

A FISH test, or fluorescence in situ hybridization, is one of the quickest ways to diagnose Williams syndrome. The FISH test uses a fluorescent marker to determine if the genes critical to Williams syndrome are present in the blood sample of your child or not. If the genes are present, the diagnosis of Williams syndrome is confirmed.

Chromosomal Microarray

A chromosomal microarray uses millions of markers to determine whether there are missing or extra pieces of DNA anywhere in an individual’s chromosomes. While chromosomal microarray is a slower test that requires more thorough analysis by a geneticist, it does provide more information about how big the missing piece is, which may affect how severely your child will experience the symptoms of Williams syndrome throughout their life.

When Is Williams Syndrome Usually Diagnosed?

Due to the recognizable physical and developmental symptoms of Williams syndrome, the disorder is usually diagnosed in children before they turn 4 years old. If you have a family history of Williams syndrome, doctors may conduct tests earlier to ensure your child does not have symptoms of the syndrome. If you begin to recognize any of the signs or symptoms of Williams syndrome in your child, speaking with your pediatrician is the best course of action. As with many genetic disorders, early diagnosis allows for early intervention, which can help your child live a happy and healthy life with Williams syndrome.

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