Down syndrome is a genetic disorder caused when abnormal cell division results in extra genetic material from chromosome 21. This genetic disorder, which varies in severity, causes lifelong intellectual disability and developmental delays, and in some people it causes health problems. Down syndrome is the most common genetic chromosomal disorder and cause of learning disabilities in children. Human cells normally contain 23 pairs of chromosomes. One chromosome in each pair comes from your father, the other from your mother. Down syndrome results when abnormal cell division involving chromosome 21 occurs. These cell division abnormalities result in extra genetic material from chromosome 21, which is responsible for the characteristic features and developmental problems of Down syndrome. Trisomy 21, Mosaic down syndrome and translocation down syndrome are the three genetic variations that causes down syndrome.
Children with Down syndrome have a distinct facial appearance. Though not all children with Down syndrome have the same features, some of the more common features are: Small head Short neck Protruded tongue Upward slanting eyes Tiny white spots on the colored part (iris) of the eye called Brushfield spots etc Children with this syndrome will be given care which includes genetic counseling for the family, social support, and educational programming appropriate for the level of intellectual functioning.
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. Down syndrome can be diagnosed prenatally with amniocentesis, percutaneous umbilical blood sampling (PUBS), chorionic villus sampling (CVS), and extraction of fetal cells from the maternal circulation. Overall, the 2 sexes are affected roughly equally. The male-to-female ratio is slightly higher (approximately 1.15:1) in newborns with Down syndrome, but this effect is restricted to neonates with free trisomy 21.