What is Down syndrome?
What is the cause and types of Down syndrome?
What is the health risk for peolpe with Down syndrome?
What about the development of person with Down syndrome?
What are the characteristic for people with Down syndrome?

What is Down syndrome?

Down syndrome is a genetic condition that causes delays in physical and intellectual development due to the presence of an extra chromosome 21, known also as Trisomy 21. Down syndrome is a chromosome irregularity caused by genetic mutation first identified by Dr. John Langdong Down in 1866 and first thought to be associated by intermarriage with the Mongol tribe - thus the name Mongoloid.

However, in 1932 de Waardenburg found that it was due to chromosome defect caused by genetic mutation at conception stage. 93 years later, in 1959, this syndrome has finally ended its journey in the laboratory and was proven and confirmed by Lejeune and coleages based on the de Waardenburg's theory. Down syndrome is the most frequent genetic cause of mild to moderate mental retardation and associated medical problems, which accurs in 1:800 live birth in all races and economic groups. However, individuals with this syndrome can lead fulfilling and productive lives.

What is the cause and types of Down syndrome?

Down syndrome is usually caused by an error in cell division called nondisjunction. It is not known why this accours. However, it is known that the error occurs at conception and it is not related to anything the mother did during pregnancy. It has been known for some time that the incidence of Down syndrome increases with advancing maternal age. However, 80% of children with Down syndrome are born to women above 35 years of age.

1. Trisomy 21 - nondisjunction is caused by a faulty cell division that results in the baby having three #21 chromosomes instead of two. Prior to or at conception, a pair of #21 chromosomes in either the egg or the sperm fails to separate properly. The extra chromosome is replicated in every cell of the body. 95% of all people with Down syndrome have Trisomy 21.
2. Translocation - accounts for only 3-4% of all cases. In translocation a part of chromosome #21 breaks off during cell division and attaches to another chromosome. The presence of an extra piece of the 21st chromosome causes the characteristics of Down syndrome. Unlike Trisomy 21 which is the result of random error in the early cell division, translocation may indicate that one of the parents is carrying chromosomal material that is arranged in an unusual manner.
3. Mosaicism - occurs when nondisjunction of chomosome #21 takes place in one of the initial cell divisions after fertilization. When this happens, there is a mixture of two types of cells, some containing 46 chromosomes and some with 47. The cells with 47 chromosomes contain an extra 21st chromosome. Because of the mosaic pattern of the cells, the term mosaicism is used. This type of Down syndrome occurs in only 1-2% of all cases of Down syndrome.

Regardless of the type of Down syndrome a person may have, a critical portion of the 21st chromosome is present in all or some of their cells. This additional genetic material alters the course of development and causes the characteristics associated with the syndrome.

What is the health risk for peolpe with Down syndrome?

Many children with Down syndrome have health complications beyond the usual childhood illness. Approximately 40% of the children have congenital heart defects. It is very important that an echocardiogram be performed on all newborns with Down syndrome in order to identify any serious cardiac problems that might be present. Some of the heart conditions require surgery while others only require careful monitoring. Children with Down syndrome have a higher incidence of infection, respiratory, vision and hearing problems as well as thyroid and other medical conditions.

However, with appropriate medical care most children and adults with Down syndrome can lead healthy lives with the average life expectancy of 55 years and with many living into their sixties and seventies.

What about the development of person with Down syndrome?

It is important to remember that while children and adults with Down syndrome experience developmental delays, they also have many talents and gifts and should be given the opportunity and encouragement to develop them.

Most children with Down syndrome have mild to moderate impairments but it is important to note that they are more like other children than they are different. Early intervention services should be provided shortly after birth. These services should include physical, speech and developmental therapies. Most children attend their neighborhood schools, some in regular classes and others in special education classes. Some children have more significant needs and require a more specialized program.

Some high school graduates with Down Syndrome participate in post-secondary education. many adults with Down syndrome are capable of working in the community, but some require a more structured environment.

What are the characteristic for people with Down syndrome?

1. Muscle Hypotenia
2. Flat Facial Profile
3. Oblique Palpebral Fissures
4. Dysplastic Ear
5. Simian Crease
6. Hyperflexibility
7. Dysplastic Middle Phalanx of the fifth finger
8. Epicanthal folds
9. Exessive space between large & second toe
10. Enlargment of tongue