Down syndrome is a genetic condition that causes delays in physical and mental growth. It occurs in 1 out of every 691 children. Individuals with Down syndrome have 47 chromosomes instead of the usual 46. It is the most commonly occurring genetic disorder. Down syndrome has nothing to do with race, nationality, or religion. Down syndrome is usually caused by an error in cell division called nondisjunction. The cause of nondisjunction is now unknown, but research has shown that it increases in regularity as a woman ages. Because of higher birth rates in younger women, at least 75% of children with Down syndrome are born to women less than 35 years old. As stated earlier, there is no scientific research which indicates that Down syndrome is caused by environmental components or the parents activities before or during pregnancy. Down syndrome can originate from both the father or the mother. Approximately 5% of the cases are already traced to the father.
Additional genetic material alters growth and causes the characteristics associated with Down syndrome. Some of the frequent physical traits of Down syndrome are low muscle tone, small size, an upward slant to the eyes, and a single deep wrinkle across the center of the hand. Keep in mind that each person with Down syndrome is unique person and may possess these characteristics to different degrees.
Down syndrome is frequently caused by an error in cell division called " non-disjunction. " Non-disjunction creates an embryo with three instances of chromosome 21 instead of the usual two. Prior to conception, a pair of 21st chromosomes in either the sperm or the egg doesn’t separate. As the embryo develops, the extra chromosome is duplicated in every cell of the baby. This type of Down syndrome, which accounts for 95% of instances, is called trisomy 21.
Mosaicism occurs when non-disjunction associated with chromosome 21 takes place within one of the initial cell divisions after fertilization. When this happens, there is a mixture of two styles of cells, some containing the 46 chromosomes and the other containing 47. Those cells with 47 chromosomes contain an extra chromosome 21. Mosaicism accounts for about 1% of cases of Down syndrome. Research has indicated that people with mosaic Down syndrome could have fewer characteristics of Down syndrome than those with other sorts of Down syndrome. Sweeping generalizations are not possible because of the wide range of abilities people with Down syndrome possess.
Translocation makes up around 4% of all people with Down syndrome. In translocation, part of chromosome 21 breaks off during cellular division and attaches to another chromosome, usually chromosome 18. While the total number of chromosomes in the cells remain forty-six, the presence of an extra part of chromosome 21 causes the features of Down syndrome. No matter what type of Down syndrome a person may have, all people with down syndrome have an extra, critical portion of chromosome 21 within all or some of their cells. This particular additional genetic material changes the course of development to result in the characteristics associated with down syndrome.
Quite a few children with Down syndrome have health complications past the usual childhood illnesses. Approximately 40% of the children get congenital heart defects. It is important that an echocardiogram be executed on all newborns having Down syndrome in order to recognize any serious cardiac conditions that may be present. Some heart conditions require surgery while others only require careful monitoring. Children with Down syndrome have got a…