Search results
Results from the WOW.Com Content Network
Down syndrome or Down's syndrome, [12] also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. [3] It is usually associated with developmental delays, mild to moderate intellectual disability , and characteristic physical features.
A guide to Down syndrome including symptoms and diagnosis of this genetic condition. ... Translocation Down syndrome can be passed from parent to child, but this is rare. In these cases, the ...
A Robertsonian translocation in balanced form results in no excess or deficit of genetic material and causes no health difficulties. In unbalanced forms, Robertsonian translocations cause chromosomal deletions or addition and result in syndromes of multiple malformations, including trisomy 13 (Patau syndrome) and trisomy 21 (Down syndrome). The ...
The second, combined with a normal gamete from the other parent, gives rise to a typical child. The third leads to a translocation Down syndrome child. The last becomes a translocation carrier, like the parent. Translocation Down syndrome is often referred to as familial Down syndrome. It is the cause of about 4.5% of the observed Down ...
A guide to Down syndrome including symptoms and diagnosis of this genetic condition. Skip to main content. Sign in. Mail. 24/7 Help. For premium support please call: 800-290 ...
For example, carriers of Robertsonian translocations involving chromosome 21 have a higher risk of having a child with Down syndrome. This is known as a 'translocation Downs'. This is due to a mis-segregation (nondisjunction) during gametogenesis. The mother has a higher (10%) risk of transmission than the father (1%).
In a small percentage of cases, Down syndrome is caused by a rearrangement of chromosomal material between chromosome 21 and another chromosome. As a result, a person has the usual two copies of chromosome 21, plus extra material from chromosome 21 attached to another chromosome. These cases are called translocation Down syndrome.
The average IQ of a young adult with Down syndrome is 50, equivalent to the mental age of an 8- or 9-year-old child, but this number varies widely. [3] At the same time, they enjoy a rich social and emotional awareness. [4] Down syndrome is the most common chromosome abnormality in humans, [3] occurring in about one per 1000 babies born each ...