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DOWN SYNDROME

Down syndrome (DS or DNS) also known as Down’s syndrome is a genetic condition. It is not an illness or a disease.  It is a set of physical and mental traits caused by a gene problem that happens before birth. It is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21.

Causes

Down syndrome is caused by having three copies of the genes on chromosome 21, rather than the usual two. The parents of the affected individual are typically genetically normal.

In every cell in the human body there is a nucleus, where genetic material is stored in genes.  Genes carry the codes responsible for all of our inherited traits and are grouped along rod-like structures called chromosomes.  Typically, the nucleus of each cell contains 23 pairs of chromosomes, half of which are inherited from each parent. Normally, a person has 46 chromosomes. But most people with Down syndrome have 47 chromosomes. Down syndrome occurs when an individual has a full or partial extra copy of chromosome 21.

This additional genetic material changes the way the brain and body develop thereby, altering the course of development and causes the characteristics associated with Down syndrome.

Types

Three types of Down syndrome exist, namely:  trisomy 21 (nondisjunction), translocation and mosaicism.

Symptoms

Some common physical features of Down syndrome include:

• A flattened face, especially the bridge of the nose

• Almond-shaped eyes that slant up

• A short neck

• Small ears

• A tongue that tends to stick out of the mouth

• Tiny white spots on the iris (colored part) of the eye

• Small hands and feet

• A single line across the palm of the hand (palmar crease)

• Small pinky fingers that sometimes curve toward the thumb

• Poor muscle tone or loose joints

• Shorter in height as children and adults