Angelman Syndrome

The characteristic symptoms of Angelman syndrome aren’t usually apparent at birth. Healthcare providers typically diagnose the condition in children between one and four years of age. But this can vary because Angelman syndrome has such a wide range of symptoms and severity.

Angelman syndrome is also easily misdiagnosed as other conditions that closely resemble it, including:

• Autism spectrum disorder.
• Cerebral palsy.
• Mowat-Wilson syndrome.
• Christianson syndrome.
• Pitt-Hopkins syndrome.
• Prader-Willi syndrome.
• Phelan-McDermid syndrome.

The only certain way to diagnose Angelman syndrome is with genetic testing that identifies changes to the UBE3A gene.

What tests are used to diagnose Angelman syndrome?

In most cases, healthcare providers diagnose Angelman syndrome in young children, but they can sometimes identify the condition prenatally (before birth).

Diagnosis of Angelman syndrome before birth

In some cases, healthcare providers can identify Angelman syndrome before your baby is born through a prenatal ultrasound. They look for signs of fetal growth issues.

Current studies have shown that noninvasive prenatal screening (NIPS) is highly accurate in the diagnosis of Angelman syndrome pre-birth. NIPS is a method of determining the risk that your baby will be born with certain genetic abnormalities. This testing analyzes small fragments of DNA that are circulating in a pregnant person’s blood.

Diagnosis of Angelman syndrome after birth

In most cases, providers diagnose Angelman syndrome in children between one and four years of age. They may suspect the condition if your child’s development is delayed and they have the syndrome’s distinctive characteristics.

Providers use a variety of specialized blood tests to confirm the diagnosis of Angelman syndrome. Laboratory scientists perform several genetic tests that look for:

• Any chromosomes or pieces of chromosomes that are missing.
• Changes in your child’s UBE3A gene that would stop it from working.
• Changes in either biological parent’s UBE3A gene that they may have passed on.

If your child has Angelman syndrome, it’s important to know the genetic change that caused it. This helps to determine whether there’s a chance you might have another child with Angelman syndrome.

Your child’s provider may also order the following tests to help with the diagnosis or to check for possible complications:

• Electroencephalogram (EEG): An EEG measures and records your child’s brain’s electrical signals. During an EEG, a technician places small metal disks (electrodes) on your child’s scalp. The electrodes attach to a machine that gives their healthcare provider information about your child’s brain’s activity. This test can show a characteristic brain activity pattern of Angelman syndrome and any epileptic activity, which can help in the diagnosis.
• Sleep study (polysomnography): This test can diagnose any sleep disorders, which are common in children with Angelman syndrome.