Other Intellectual Disabilities

A wide range of conditions can lead to intellectual disabilities. As a Special Olympics athlete put it, "No one overcomes more than we do and still loves life so much." Here's a look at other types of conditions that some of our athletes face.

Apert Syndrome


Apert syndrome is a genetic disease in which the seams between the skull bones close earlier than normal. This affects the shape of the head and face.

Apert syndrome can be passed down through families (inherited). The syndrome is inherited as an autosomal dominant trait, which means that only one parent needs to pass on the faulty gene for a child to have the condition.

Some cases may occur without a known family history.

Apert syndrome is caused by mutations in a gene called fibroblast growth factor receptor 2. This gene defect causes some of the bony sutures of the skull to close too early, a condition called craniosynostosis.

Symptoms include fusion or severe webbing of the 2nd, 3rd, and 4th fingers; webbing or fusion of toes; hearing loss; slow intellectual development; prominent eyes; under-development of the mid-face; skeletal (limb) abnormalities; and small stature.

Williams Syndrome


Williams syndrome is a developmental disorder that affects many parts of the body. This condition is characterized by mild to moderate intellectual disability or learning problems, certain personality characteristics, distinctive facial features, and heart and blood vessel (cardiovascular) problems.

Williams syndrome is caused by the deletion of genetic material from a specific region of chromosome 7. The deleted region includes more than 25 genes.

People with Williams syndrome typically have difficulty with visual-spatial tasks such as drawing and assembling puzzles, but they tend to do well on tasks that involve spoken language, music, and learning by repetition (rote memorization). Affected individuals have outgoing, engaging personalities and tend to take an exceptional interest in other people. Attention deficit disorder (ADD), problems with anxiety, and phobias are common among people with this disorder.

Young children with Williams syndrome have distinctive facial features including a broad forehead, a short nose with a broad tip, full cheeks, and a wide mouth with full lips. Many affected people have dental problems such as small, widely spaced teeth and teeth that are crooked or missing. In older children and adults, the face appears longer and more gaunt.

A form of cardiovascular disease called supravalvular aortic stenosis (SVAS) occurs frequently in people with Williams syndrome. SVAS is a narrowing of the large blood vessel (the aorta) that carries blood from the heart to the rest of the body. If this condition is not treated, the aortic narrowing can lead to shortness of breath, chest pain, and heart failure. Other problems with the heart and blood vessels, including high blood pressure (hypertension), have also been reported in people with Williams syndrome.

Additional signs and symptoms of Williams syndrome include abnormalities of connective tissue (tissue that supports the body's joints and organs) such as joint problems and soft, loose skin. Affected people may also have increased calcium levels in the blood (hypercalcemia) in infancy, developmental delays, problems with coordination, and short stature. Medical problems involving the eyes and vision, the digestive tract, and the urinary system are also possible.

Fetal Alcohol Syndrome


Fetal alcohol spectrum disorders (FASDs) are a group of conditions that can occur in a person whose mother drank alcohol during pregnancy. These effects can include physical problems; difficulty with behavior and learning; or a mixture of all three.

Signs of FASDs can be physical or intellectual. That means they can affect the mind or the body, or both. Because FASDs make up a group of disorders, people with FASDs can show a wide range and mix of signs.

Physical signs of FASDs can include abnormal facial features such as narrow eye openings and a smooth philtrum (the ridge between the upper lip and nose), small head size, short stature, and low body weight. In rare cases, there are problems with the heart, kidneys, bones, or hearing.

Intellectual and behavioral signs of FASDs might include problems with memory, judgment or impulse control, motor skills, academics (especially in math), paying attention, and low IQ. Specific learning disabilities are also possible.



Prader-Willi syndrome is the most common of the genetic disorders that cause life-threatening obesity in children. The syndrome affects many aspects of a person's life including eating, behavior and mood, physical growth, and intellectual development.

The syndrome usually results from deletions or partial deletions on chromosome 15 that affect the regulation of gene expression, or how genes turn on and off. Andrea Prader and Heinrich Willi first described the syndrome in the 1950s.

One of the main symptoms of Prader-Willi syndrome is the inability to control eating. Other symptoms include low muscle tone and poor feeding as an infant, delays in intellectual development, and difficulty controlling emotions.

Individuals with Prader-Willi syndrome have varying levels of intellectual disabilities. Learning disabilities are common, as are delays in starting to talk and in the development of language.

Phenylketonuria (PKU)


Phenylketonuria (pronounced fen-l-kee-toh-NOOR-ee-uh), or PKU, is an inherited disorder that that can cause intellectual and developmental disabilities (IDDs) if untreated. In PKU, the body can't process part of a protein called phenylalanine, which exists in all foods containing protein. If the phenylalanine level gets too high, the brain can become damaged.

All children born in U.S. hospitals are tested routinely for PKU soon after birth, making it easier to diagnose and treat early. Children and adults who are treated early and consistently develop normally. Depending on the level of phenylalanine and tolerance for phenylalanine in the diet, PKU is classified into two different types: classic (which is the severe form) and moderate.

Children with untreated PKU appear normal at birth. But by age 3 to 6 months, they begin to lose interest in their surroundings. By age 1 year, children are developmentally delayed and their skin has less pigmentation than someone without the condition. If people with PKU do not restrict the phenylalanine in their diet, they develop severe intellectual and developmental disabilities.

Other symptoms include: behavioral or social problems; seizures, shaking, or jerking movements in the arms and legs; stunted or slow growth; skin rashes, such as eczema; small head size (microcephaly); musty odor in urine, breath, or skin that is a result of the extra phenylalanine in the body; and fair skin and blue eyes, due to the body's failure to transform phenylalanine into melanin.

Cerebral Palsy


The term cerebral palsy refers to any one of a number of neurological disorders that appear in infancy or early childhood which permanently affect body movement and muscle coordination, but don’t worsen over time. Even though cerebral palsy affects muscle movement, it isn’t caused by problems in the muscles or nerves. Rather, it is caused by abnormalities in parts of the brain that control muscle movements.

The majority of children with cerebral palsy are born with it, although it may not be detected until months or years later. The early signs of cerebral palsy usually appear before a child reaches 3 years of age. The most common are a lack of muscle coordination when performing voluntary movements (ataxia); stiff or tight muscles and exaggerated reflexes (spasticity); walking with one foot or leg dragging; walking on the toes, a crouched gait, or a “scissored” gait; and muscle tone that is either too stiff or too floppy.

A small number of children have cerebral palsy as the result of brain damage in the first few months or years of life; brain infections such as bacterial meningitis or viral encephalitis; or head injury from a motor vehicle accident, a fall, or child abuse.

People with CP have problems with movement and posture. Many also have related conditions such as intellectual disability; seizures; problems with vision , hearing, or speech; changes in the spine (such as scoliosis); or joint problems (such as contractures).

Sources: The Eunice Kennedy Shriver National Institute of Child Health and Human Development and the National Institutes of Health, the American Association of Intellectual and Developmental Disabilities, and the Centers for Disease Control and Prevention, and Special Olympics.

This information came from Special Olympics.