Rett Syndrome vs Angelman Syndrome: What’s the Difference?

Rett syndrome and Angelman syndrome are similar in many ways. However, the progression of the disease is very different in both. Rett syndrome and Angelman syndrome both have some autistic features. A lot of interventions for these conditions are similar. However, they are very different clinically, and the functional level of a person with Rett's is very different from a person with Angelman. This article on Rett syndrome vs Angelman syndrome will help making the right diagnosis in every situation.

Genetic Mutation

Rett Syndrome and Angelman syndrome are caused by different genetic mutations. Thus genetic testing is the best way to confirm diagnosis of either condition. However, Rett syndrome is a single gene disorder whearas the mechanism of Angelman’s has not been completely understood. In fact 20% of people with Angelman’s may have normal genetic testing results.


Angelman syndrome is seen in both boys and girls. Rett syndrome is seen mainly in girls. This article explains why.

First Few Years of Life

Children with Angelman’s may be diagnosed as Rett's, or vice versa between 1-3 years of age. This is because some symptoms at this stage – especially hypotonia, seizure disorder, unstable gait and mild microcephaly – are seen in both conditions. However, by 3 years of age or so, stereotypical hand movements develop in Rett's.


Children with Angelman’s have mild cognitive impairments compares to children with Rett syndrome. People with Angelman’s are able to be a lot more functional in their daily activities. The only exception is when people with Angelman syndrome also have severe seizures which cause cognitive deficits.


Both Angelman’s and Rett syndrome cause severe communication difficulties. Both have some receptive and non verbal communication intact which can be used with assistive technology for functional communication

Movement Disorders

Both Angelman’s syndrome and Rett syndrome cause movement disorders. However these are specific to each condition and can aid diagnosis. People with Angelman syndrome usually have balance difficulties, including Ataxia. However, they are usually able to walk. However, with Rett's, people lose their mobility by the third or fourth stage. This is usually due to severe apraxia. Children with Rett syndrome have stereotypical hand movements.


Both Angelman syndrome and Rett syndrome are associated with seizures. However, this can make diagnosis difficult. This is because seizures can cause other symptoms and complications which change the clinical picture. Thus, it is very important to take this into consideration while diagnosing either condition.

A clear understanding of Rett syndrome vs Angelman syndrome will help correct diagnosis as well as treatment planning. For further reading, Here are some more resources on Rett syndrome.


Michael Fitzgerald, A. C. (2001). Diagnosis and differential diagnosis of Asperger syndrome. Advances in Psychiatric treatment , 310–318.

Rett syndrome: new clinical and molecular insights. (2009). European Journal of Human Genetics , 896–903.

Williams, C. A. (2001). Angelman Syndrome: Mimicking Conditions and Phenotypes. American Journal of Medical Genetics , 59- 64.