Angelman Syndrome: Definition, Symptoms & Causes

Instructor: Heidi Howerton

Heidi has written education material for a well known hospital's pediatric neurosurgery unit and has her Bachelor's of Science degree in nursing.

In this lesson, we'll learn what Angelman syndrome is and examine the genetic changes that are known to cause Angelman syndrome. We'll also discuss what symptoms a person can expect a child with Angelman syndrome to have throughout his or her lifetime.

What is Angelman Syndrome?

Have you ever wondered what Angelman syndrome is, what causes it, and what the life of a child with this syndrome might resemble? In this lesson, we'll work to explain this syndrome, it's causes, and the symptoms that accompany it.

Angelman syndrome is a genetic illness that often affects the nervous system and results in developmental disabilities and neurological problems. This syndrome is present from the time a child is born and continues with the child through the remainder of his or her life. It's rare and only occurs in about one in every 10,000 to one in every 20,000 births.

Angelman syndrome was first discovered in 1965 by a physician named Harry Angelman. As you can see, the syndrome was named after this doctor. Most parents of children with this syndrome begin noticing that something is different about their child between the ages of six to 12 months, and most cases of Angelman syndrome are diagnosed when a child is between the ages of three and seven years old.

Causes of Angelman Syndrome

Angelman syndrome is caused by a deletion or change on chromosome 15. Within each person's body there are millions of cells, and each cell contains a set of instructions, or road map, that tell our bodies how to grow, what to do, and how to work. This set of instructions is known as DNA. DNA tightly twisted around each other into strands make up chromosomes.

Humans have 46 chromosomes in each of their cells that are divided into 23 pairs. Children receive one set of chromosomes from their mother and one set of chromosomes from their father. Scientists have discovered that Angelman syndrome occurs when there's something wrong with chromosome 15.

The most common chromosomal cause of Angelman syndrome is when a portion of chromosome 15 (the side inherited from the child's mother) is deleted. While the mother has a normal chromosome 15, somehow a portion of her child's chromosome 15 is deleted when the egg first forms. These changes are genetic and entirely outside the mother's and father's control.

Other chromosomal changes that can cause Angelman syndrome, but aren't as common, include a change of the mother's chromosome 15, and when a child inherits two pairs of chromosome 15 from his or her father instead of only one. Furthermore, sometimes the exact cause is never discovered.

Symptoms of Angelman Syndrome

A deletion or mutation on chromosome 15 can cause a number of different symptoms. Some of the most frequent symptoms of Angelman syndrome include delayed development, difficulty with motor activities (such as crawling, walking, balancing, and writing), difficulty with speech, intellectual disability, and stiff body movements. Many children with Angelman syndrome also experience seizures, and have a small-sized head for their age range.

If you ever meet a child with Angelman syndrome, you'll most likely notice that he or she has a happy, loving, and busy personality. Children with Angelman syndrome are known to frequently have smiles on their faces and laughter in their bellies! This joyful personality is a symptom of Angelman syndrome.

Children with this syndrome laugh easily, enjoy being around others, flap their arms, and can be hyperactive. Sometimes a child can be so excited that it's hard for his or her parents to calm the child down and encourage the child to sleep. Sleeping problems, however, are known to get better as the child grows.

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