Down syndrome is a set of physical and mental traits caused by a gene problem that happens before birth. Children who have Down syndrome tend to have certain features, such as a flat face and a short neck. They also have some degree of intellectual disability. This varies from person to person.
Signs and symptoms
Symptoms include cognitive behavioral problems like Short attention span, poor judgment, impulsive behavior, slow learning, delayed language and speech development etc.
The extra chromosome 21 affects almost every organ system and results in a wide spectrum of phenotypic consequences. These include life-threatening complications, clinically significant alteration of life course (eg, intellectual disability), and dysmorphic physical features. Down syndrome decreases prenatal viability and increases prenatal and postnatal morbidity.
Down syndrome is the most common autosomal abnormality. The frequency is about 1 case in 800 live births. Each year, approximately 6000 children are born with Down syndrome. It is the genetic cause of developmental delay in humans, affecting approximately 1 in 700 liveborn infants in the Netherlands.