Down syndrome

Head | Neurology | Down syndrome (Disease)


Description

Down syndrome (also known as trisomy 21) is a genetic condition in which the person has an extra copy of chromosome 21. This additional chromosome results in a number of physical and developmental characteristics and some level of intellectual disability.

Down syndrome is one of the most common genetic birth defects, affecting approximately one in about 800 babies. Life expectancy among adults with Down syndrome is about 60 years, though average lifespan varies.

A child with Down syndrome may have eyes that slant upward and small ears that may fold over slightly at the top. Their mouth may be small, making the tongue appear large. Their nose also may be small, with a flattened nasal bridge. Some babies with Down syndrome have short necks and small hands with short fingers. Rather than having three creases in the palm of the hand, a child with Down syndrome usually has one single crease that goes straight across the palm, and a second crease that curves down by the thumb. The child or adult with Down syndrome is often short and has unusual looseness of the joints. Most children with Down syndrome will have some, but not all, of these features.

Causes and Risk factors

Down syndrome has genetic cause. The person has an extra copy of chromosome 21, which will be the origin of the disease.

Diagnosis and Treatment

The diagnosis of Down syndrome can be made before birth using one of several diagnostic tests. These tests carry a small risk of miscarriage. If Down syndrome is suspected after a child is born, a diagnosis can be made via chromosome analysis.

Although the genetic cause of Down syndrome is known, there is currently no cure. Due to advances in technology, scientists are slowly beginning to understand which genes when present in three copies are responsible for which Down syndrome characteristics, but it will take many years to fully grasp the complex interplay between the different genes. Much research to date is focused on understanding the causes of impaired cognition in Down syndrome and on finding potential therapies that might improve learning. ...