Angelman Syndrome and Obesity

Patients with Angelman syndrome may have a tendency to become obese. A 2017 study reported that roughly a third of Angelman syndrome patients were overweight or obese.

What is obesity?

Obesity is defined as a body mass index (BMI) of 30 or higher. BMI is the ratio of a person’s weight in pounds over the square of their height in inches times 703.

Multiple factors may contribute to obesity, such as a genetic predisposition, limited access to exercise, and hyperphagia (an abnormally strong desire to eat).

Obesity can increase the risk of medical problems such as diabetes or heart disease. It is a major health concern among adults with Angelman syndrome.

How can Angelman syndrome cause obesity?

One study proposed a couple of explanations for the abnormal eating behaviors exhibited by Angelman syndrome patients.

Alterations in the dopamine pathway of patients, resulting in pleasure-seeking by eating food, was one possible mechanism. Dopamine is a neurotransmitter (a chemical that sends messages between nerve cells) and is associated with feelings of pleasure and reward.

The second proposal concerned complementary foods. These are soft foods such as porridge and baby food given during infancy to wean babies. Children with Angelman syndrome may have a strong preference for this type of food and continue to desire them as they grow and refuse other types of foods. During this time, they may also exhibit hyperphagia and behaviors such as stealing their preferred foods.

Which patients may be at a higher risk?

Research has shown a higher rate of obesity in Angelman syndrome patients among infants and toddlers with paternal disomy or genomic imprinting issues compared to patients with mutations in the UBE3A gene.

Paternal disomy is where the child inherits two copies of chromosome 15 (which contains the UBE3A gene) from the father, instead of one copy from the father and the other from the mother.

Genomic imprinting is a process that labels the mother’s and father’s genes. Only the copy from one parent is active in some cells of the body. For example, only the maternal copy of the UBE3A gene is active in many cells of the brain and is essential for healthy development. In some patients, the maternal UBE3A gene is still present but is mislabeled as the paternal copy (genomic imprinting defect) and therefore is not active, resulting in the syndrome.

Last updated: Dec. 21, 2020

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