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What causes developmental delay and mental retardation? 8 possible conditions

See a list of possible causes in order from the most common to the least.


Mental Retardation

Mental retardation or intellectual disability, (MR/ID), exists in children whose brains do not develop properly or function within the normal range. There are four levels of retardation: mild, moderate, severe, an...

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Down Syndrome

Down syndrome is the most common genetic condition in the United States. It causes physical and mental developmental delays and disabilities.

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Cerebral Palsy

Cerebral palsy is a disorder of muscle movement and coordination caused by an injury to a child's brain that occurs before birth or during infancy. It affects the part of the brain that controls body movement. Othe...

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Hydrocephalus is a condition that occurs when fluid builds up in the skull and causes the brain to swell. The name literally means "water on the brain."

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Muscular Dystrophies

Muscular dystrophies are a group of inherited diseases that damage and weaken your muscles over time. This damage and weakness is due to the lack of a protein.

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Homocystinuria is an inherited disorder that keeps the body from processing the essential amino acid methionine. Amino acids are the building blocks of protein. Methionine occurs naturally in various proteins. It i...

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Phenylketonuria is a rare genetic condition in which the body is unable to breakdown phenylalanine, an essential amino acid.

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Tuberous Sclerosis

Tuberous sclerosis (TS) is a rare genetic condition. Sometimes called tuberous sclerosis complex (TSC), the disorder causes noncancerous (benign) tumors to grow in the brain and other vital organs, and on the skin...

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This feature is for informational purposes only and should not be used to diagnose.
Please consult a healthcare professional if you have health concerns.