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Down’s syndrome is one of the most common conditions leading to mental disability. New scientific data revealed the molecular mechanism behind this disease. The possibility to develop a cure for Down’s syndrome was demonstrated on experimental animals.

Down’s syndrome is the most common chromosomal abnormality which leads to a mental condition associated with intellectual disabilities. Disease, also known as trisomy 21, is caused by additional copy of chromosome 21 present in all cells of the body of affected person.

Down’s syndrome severely affects mental and physical abilities

Down’s syndrome is usually associated with delays in mental development and physical growth, as well as characteristic and recognizable facial features. The IQ of the young individuals with Down’s syndrome is usually around 50, while the normal young adults have average IQ of 100. People with Down’s syndrome often demonstrate speech delays and delayed motor skills (problems with learning how to walk in childhood are very typical). They are also often affected by various heart conditions.

The symptoms of Down’s syndrome are associated with the presence of additional copies of genes coming from the third chromosome 21. This chromosome is one of the smallest in our cells and codes for approximately 200-250 genes. Excessive genetic material causes over-expression of certain genes and presence of excessive amounts of protein products of these genes. Excessive quantities of these proteins disrupt normal regulation of many biochemical processes and bodily functions.

The presence of additional genetic material can have different medical consequences and can damage various organs in the body. This results in significantly lower average life expectancy for people affected by this condition, which stands now at approximately 60 years. Towards the older age, people with Down’s syndrome tend to develop neurodegenerative diseases and suffer from dementia. Researchers have recently identified the genes that are responsible for clinical manifestations of Down’s syndrome and cause the biggest problems for people having this condition.

Gene therapy bring hope to people with Down’s syndrome

Genetic conditions like Down’s syndrome are hard to treat and impossible to cure at present time. Any attempts to cure must somehow address the problem of additional genetic material in the cells of affected individuals. However, the progress of gene therapy in recent years brings hope that our understanding of gene functioning on the level of whole body will eventually result in the development of genetic tools capable to address this problem. Now we are already able to activate or suppress certain genes in the body, and although most of this work is done on experimental animals, the development of appropriate and safe tools for manipulations with human genome is only a matter of time.

Till recently, the exact mechanism leading to learning disabilities and delay in physical growth in patients with Down’s syndrome was unknown. New findings announced by scientists from California and published in Nature Medicine seem to give answer to this question.

Continue reading after recommendations

  • Wang, X., Zhao, Y., Zhang, X. et al. (2013) Loss of sorting nexin 27 contributes to excitatory synaptic dysfunction by modulating glutamate receptor recycling in Down's syndrome. Nature Medicine. Published online 24 March 2013. doi:10.1038/nm.3117
  • Cai L, Loo LS, Atlashkin V, Hanson BJ et al. (2011) Deficiency of sorting nexin 27 (SNX27) leads to growth retardation and elevated levels of N-methyl-D-aspartate receptor 2C (NR2C). Mol Cell Biol. 31(8):1734-47
  • Photo courtesy of Down Syndrome Dreams by Picasa :
  • Photo courtesy of Walter Parenteau by Flickr :
  • Matt W Jones (2013) Sorting receptors at Down's syndrome synapses. Nature Medicine 19, 404–406
  • Zohra Rahmani, Jean-Louis Blouin, Nicole Créau-Goldberg et al. (2005). Down syndrome critical region around D21S55 on proximal 21q22.3. American Journal of Medical Genetics 37 (S7): 98–103

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