Down syndrome is a genetic disorder with abnormality in number of chromosomes where extra genetic material from chromosome 21 is transferred to a newly formed embryo, having 47 chromosomes in their cells instead of 46 (Normal number of Chromosomes), characterized by intellectual disability, a characteristic facial appearance, and weak muscle tone (hypotonia) in infancy. All affected individuals experience cognitive delays but the intellectual disability is usually mild to moderate. All person with Down syndrome are unique individual and may be characterized to different degrees, or not at all.
Every cell in the body comprises genes that are grouped along chromosomes in the nucleus of the cell. There are usually 46 number of chromosomes in each cell, 23 are inherited from mother and 23 from father. But in case of Down syndrome there is an extra full or partial copy of chromosome 21 some or all cells.
Trisomy 21
Every cell of the affected child have three copies of chromosome 21 instead of the usual two copies. Affecting about 95 percent of people.
Mosaic Down syndrome
Type of Condition where child is born with an extra chromosome in some of the cells not all. It's a rare form of Down syndrome affecting about 2% of people
Translocation Down syndrome
It's a type where one of every cell has an extra piece of chromosome 21 attaches itself to another chromosome. It affects around 4% of people with Down's syndrome.
Individuals with Down syndrome often have different physical characteristics, distinctive health issues, and variability in cognitive development.
Physical appearance
Individual of Down's syndrome are often characterized by certain physical features which may not be present in everyone, but they may have:
Delayed development
Health problems