SCIENTIFIC BACKGROUND

trisomy 21

Category:

Scientific background

Down syndrome is caused by an additional chromosome 21 (trisomy 21). Life expectancy has increased significantly in recent years, but is reduced by about 20 years compared to the general population. Clinical symptoms include intellectual disability, typical facial features (epicanthus, upward slanting eyes, macroglossia), cardiac abnormalities, muscle hypotonia, sandal gap, and a single transverse palmar crease. Females with Down syndrome are fertile, whereas males are usually infertile. An increased susceptibility to infections and a slightly increased risk of childhood leukemia are characteristic of Down syndrome.

 

There are very good support options available for those with Down syndrome to help them achieve a high degree of independence in adulthood. Nevertheless, most adults with Down syndrome are reliant on support in their daily lives. Down syndrome occurs with an average incidence of 1:650 newborns, although there is a maternal age effect (incidence 1:1,250 in a 20-year-old woman and 1:90 in a 40-year-old woman). In 92% an additional chromosome 21 is present (free trisomy 21), 3% show a mosaic trisomy 21 and in 5% a so-called Robertsonian translocation between a third chromosome 21 and an acrocentric chromosome is found (so-called hereditary variant of Down syndrome). Partial trisomies due to other translocations are very rare.

 

References

Antonorakis et al. 2004, Nature Rev Genet 5:725 / Stripoli et al. 1999, Genomics 64:252 / Yamakawa et al. 1998, Hum Molec Genet 7:227 / Baird and Sadovnick 1988, Lancet 2:1354 / Pellisier et al. 1988, Hum Genet 80: 277

GENES

trisomy 21
How to order

LATEST ARTICLES

Have you ever wondered how jet-setting across the globe might affect your gut health? A recent study has dug into this intriguing question, revealing...

Read more

In June 2023, Medicover Genetics attended the 56th conference of the European Society of Human Genetics (ESHG) which took place in Glasgow, Scotland....

Read more

Vitamin D, also known as “the sunshine vitamin”, is a fat-soluble vitamin that helps the body absorb calcium and phosphate, which are essential f...

Read more

Every movement our body makes is controlled by a long, thin, tube-like structure called the “spinal cord”. The spinal cord is part of our nervous...

Read more

Genetic variant databases are vital for interpreting genetic variations in clinical settings and research. However, misclassified variants can create...

Read more

A recent article published by our team in the International Journal of Molecular Sciences [1], aimed to evaluate the prevalence, prognostic and predi...

Read more

A healthy, nutritious and well-balanced diet is always important for a person’s well-being, and it is even more so during pregnancy as the developi...

Read more

The sun is hot and you are sweating. Most of us know how it feels to sweat, and when we sweat. This is a normal bodily response to an increase in tem...

Read more

All about the pancreas The pancreas is a pear-shaped organ that is located at the upper left side of the abdomen, behind the stomach. It has two m...

Read more

The father of genetics is Gregor Mendel. Mendel was an Austrian monk, whose experiments breeding pea plants in the monastery garden led to breakthrou...

Read more