Tests and diagnosis

By Mayo Clinic Staff

Your child's doctor may suspect Angelman syndrome if your child has developmental delays and other signs and symptoms of the disorder, such as problems with movement and balance, small head size, flatness in the back of the head, and frequent laughter.

Confirming a diagnosis of Angelman syndrome requires taking a blood sample from your child for genetic studies. A combination of genetic tests can reveal the chromosome defects related to Angelman syndrome. These tests may look at:

  • Parental DNA pattern. This test, known as a DNA methylation test, screens for three of the four known genetic mechanisms that cause Angelman syndrome.
  • Missing chromosomes. Either a fluorescence in situ hybridization (FISH) test or a comparative genomic hybridization test (CGH) can show if portions of chromosomes are missing.
  • Gene mutation. Rarely, Angelman syndrome may occur when a person's maternal copy of the UBE3A gene is active, but mutated. If results from a DNA methylation test are normal, your child's doctor may order a UBE3A gene sequencing test to look for a maternal mutation.
Dec. 05, 2014

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