Down's syndrome, also known as Down syndrome or trisomy 21, is a genetic condition that typically causes some level of learning disability and certain physical characteristics.

Down's syndrome is a genetic condition that happens as a result of an extra chromosome (chromosome 21).

Usually, cells contain 46 chromosomes – 23 from the mother and 23 from the father.

In people with Down's syndrome, all or some of the cells in their bodies contain 47 chromosomes instead, as there's an extra copy of chromosome 21. This extra gene causes the characteristics of Down's syndrome.

In most cases, Down's syndrome isn't inherited, it's just the result of a one-off genetic change in the sperm or egg.

Each person with Down's syndrome is affected differently, but most share certain physical characteristics and development problems. the most common :
• Small head.
• Short neck.
• Flatten the back of the head.
• protruding large tongue .
• Slanted eyes upward.
• Small ears.
• Short arms.
• single palm line.
• relatively short fingers .
• Small white spots on the colored part (iris) of the eye is called Brush field spots.
• Short stature.

With help and support, most people with Down's syndrome are able to have healthy, active and more independent lives.

-  heart problems
- Leukemia
- Infectious diseases
- Dementia .
- sleep apnea
- Obesity
- Other health problems: Down syndrome are associated with other health problems, including blockage of the gastrointestinal tract, and thyroid problems,early menopause in women , convulsions, inflammation of the ear, hearing loss, poor eyesight, and skin problems such as psoriasis .