Phelan-mcdermid syndrome

Symptoms

What behavior problems to children with Phelan-McDermid syndrome exhibit?

Children with Phelan-McDermid syndrome have been described as having "autistic-like" behavior. They are anxious in social situations, don't like to be touched, avoid eye contact, and exhibit repetitive body movements. Other behavioral traits mouthing or chewing of non-food items and decreased perception of pain.

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Do all newborns with Phelan-McDermid syndrome have low muscle tone?

What facial and physical differences are usually seen in Phelan-McDermid syndrome?

Can people with Phelan-McDermid syndrome talk?

Do people with Phelan-McDermid syndrome typically have hearing loss?

What is the growth pattern in people with Phelan-McDermid syndrome?

What are less common medical concerns seen in people with Phelan-McDermid syndrome?

Is everyone with Phelan-McDermid syndrome affected the same?

Do all people with a chromosome 22q13.3 deletion in every cell have clinical features of Phelan-McDermid syndrome?

Do all newborns with Phelan-McDermid syndrome have low muscle tone?

More than 95% of newborns with Phelan-McDermid syndrome have low muscle tone (hypotonia). Babies with hypotonia may appear floppy. This low muscle tone can lead to poor head control, feeding difficulties, failure to thrive (failure to gain weight), and a weak cry. If you have a baby with these features, talk to your doctor about the possibility of working with a physical therapist to help strengthen the muscles.

What facial and physical differences are usually seen in Phelan-McDermid syndrome?

Facial differences seen in Phelan-McDermid syndrome include a flattened middle of the face, droopy eyelids (ptosis), puffy eyelids and cheeks, long eyelashes, a wide nasal bridge (area between the eyes), a bulbous nose, a pointed chin, large ears, a long head relative to the width (dolichocephaly), and full eyebrows. Physical differences can include large fleshy hands and/or feet, small and/or abnormal toenails, fusion of the second and third toes (syndactyly), and fast growth. Not everyone with Phelan-McDermid syndrome will have these features. If you feel your child has many of these features, talk to your doctor about visiting a medical geneticist to discuss testing for Phelan-McDermid syndrome.

Can people with Phelan-McDermid syndrome talk?

Most infants with Phelan-McDermid syndrome will babble at an expected age, and as they get older they may develop a limited amount of speech. By the time a child is around 4 years old, they typically lose their ability to speak. Children can learn to communicate and may be able to regain some of their ability to speak with intensive occupational, speech and physical therapy. Although speech remains impaired throughout life, individuals can learn to communicate with the help of aggressive therapy and communication training. If your child has Phelan-McDermid syndrome talk to your doctor about where to get occupational, speech and physical therapy in your area.

Do people with Phelan-McDermid syndrome typically have hearing loss?

About 80% of people with Phelan-McDermid syndrome have normal hearing. Sometimes it can appear that someone with Phelan-McDermid syndrome has hearing loss because they have delayed responses to verbal signals and difficulty noticing differences between spoken words and background noise. Repeated ear infections may also impact a person’s hearing. It is important that a person with Phelan-McDermid syndrome have formal hearing evaluations. Talk to your doctor to find out where you can get hearing testing by an audiologist in your area.

What is the growth pattern in people with Phelan-McDermid syndrome?

Growth before birth is typically normal for babies with Phelan-McDermid syndrome. Once a baby is born, growth may be normal or increased. People with Phelan-McDermid syndrome are usually taller than their peers, but their weight is not increased. Therefore, children can appear tall and thin. For adults with Phelan-McDermid syndrome, height and weight are usually normal. About 10% of adults are overweight due to lack of activity and overeating. Head size is typically normal in all age groups. Less than 5% of affected people have a small head size (microcephaly). Talk to your doctor about ways to manage eating in an individual with Phelan-McDermid syndrome.

What are less common medical concerns seen in people with Phelan-McDermid syndrome?

Less common medical concerns seen in people with Phelan-McDermid syndrome include: Eyes that don't face in the same direction at the same time (strabismus), kidney problems, gastroesophageal reflux (GERD), frequent vomiting and nausea, seizures, abnormal alignment of the upper and lower teeth, and widely-spaced teeth. Talk to your doctor about how to treat any of these symptoms.

Is everyone with Phelan-McDermid syndrome affected the same?

Not all people with Phelan-McDermid syndrome will have the same symptoms and it is difficult to predict medical concerns at birth. Some people are more mildly affected and some people have more severe symptoms. Almost all people with Phelan-McDermid syndrome will have speech delay/absent speech, developmental delay, and intellectual disability. Children with Phelan-McDermid syndrome should be seen by a speech therapist, physical therapist, and occupational therapist to help monitor their development and provide therapy as soon as a delay is noticed.

Do all people with a chromosome 22q13.3 deletion in every cell have clinical features of Phelan-McDermid syndrome?

Some features of Phelan-McDermid syndrome are present in all individuals who have a chromosome 22q13.3 deletion in all of their cells. Individuals who have smaller chromosome 22q13.3 deletions have been reported to have milder features, but speech delay/impairment and intellectual disability are still present. To find out more about the size of the deletion in a individual with Phelan-McDermid syndrome, ask your doctor or see a medical geneticist or genetic counselor.

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