What condition is associated with severe mental retardation?

Fragile X syndrome, also called X‐linked mental retardation, causes developmental delays in male maternal relatives and is the most common inherited form of mental retardation. Trisomy 21, also known as Down syndrome, is the most common genetic cause of mental retardation.

What are the different categories of mental retardation?

The DSM-IV classifies mental retardation into four stages based on severity: mild (IQ score of 50-55 to approximately 70), moderate (IQ score of 30-35 to 50-55), severe (IQ score of 20-25 to 35-40), and profound (IQ score of less than 20-25).

What are the different types of developmental disorders?

Some types of developmental disorders include:

• ADHD.
• Autism spectrum disorder.
• Cerebral palsy.
• Hearing loss.
• Intellectual disability.
• Learning disability.
• Vision impairment.

What is the most common known biological cause of intellectual disability?

The most common known preventable or environmental cause of intellectual disability is fetal alcohol syndrome, the most common chromosomal cause is Down syndrome, and the most common genetic cause is Fragile X syndrome.

What are the 4 main types of developmental disorders?

There are four main types of developmental disorders: nervous system disabilities, sensory related disabilities, metabolic disabilities and degenerative disorders. Many different subsets of disabilities nest under these four main groups.

When are developmental disabilities diagnosed?

Developmental Disability: A Definition Most developmental disabilities are present at birth and may be identified early in life, although some developmental conditions may not be recognized until after age three.

What is the most prevalent cause of intellectual disabilities?

The most common causes of intellectual disability are:

• Genetic conditions. These include things like Down syndrome and fragile X syndrome.
• Problems during pregnancy.
• Problems during childbirth.
• Illness or injury.
• None of the above.