DOWN SYNDROME: IMPORTANT EVIDENCE IN THE FULFILLMENT OF THE COMPLETE GENETIC MAP

Down Syndrome is caused by a genetic anomaly in which there are 47 chromosomes present instead of 46, specifically the presence of an extra copy of chromosome 21 in which there are three copies of this chromosome instead of two (also known as trisomy 21). People with this syndrome may present genetic abnormalities from birth, such as minor anomalies of the skull, face, ears and hands,  that are sometimes associated with a slight reduction in muscle tone.

These malformations are often associated with a modest growth deficiency, delayed motor and language development and moderate or severe mental retardation. Also the organic disorders that may occur in adulthood include- congenital and acquired cardiac anomalies (30%), chronic lung disease (30%), epilepsy (37%), Alzheimer type presenile dementia (42%), osteoporosis  that results in the fracture of long bones(50%), acquired sensory deficits (50%), behavioral problems (50%), and loss of cognitive abilities (55-75%) (Van Allen e Coll., 1999).

For many years researchers worked to understand which genes are responsible for clinical manifestations of Down Syndrome and to try to improve conditions and life expectancy of those individuals affected.

The Institute of Genetics and Biophysics (IGB) “Adriano Buzzati Traverso” of the National Research Council (CNR) based in Naples has obtained a complete profile of genes showing the defects of people with down syndrome through the use of technology and an innovative protocol, characterized by a process of ‘mass sequencing’ (deep sequencing) on a large scale that requires close interaction between advanced skills in molecular biology and bioinformatics. It is a tool that uses sophisticated computer technology capable of the genetic mapping of a sample taken from an individual in a few weeks. A group coordinated by Prof. Ciccodicola conducted a study that was publish in the journal PLos ONE in April 2011. The researchers found that not only genes in chromosome 21 are responsible for the syndrome, but also that their interaction with other genes are responsible in determining the disease manifestations.

An important aspect is the identification by the study center, in CNR, of how certain genes in the cells of those with Down Syndrome are regulated in their expression by small portions of molecular RNA.

High resolution mapping obtained by Italian researchers, which is still very expensive, constitutes an important technological advance and a basis for future clinical applications to improve the quality of life through applications in the preventive and pharmaceutical fields.

 

Riferimenti:

- van Allen MI, Fung J, Jurenka SB. Health care concerns and guidelines for adults with Down syndrome. Am J Med Genet. 1999 Jun 25;89(2):100-10.
- Costa V, Angelini C, D’Apice L, Mutarelli M, Casamassimi A, Sommese L, Gallo MA, Aprile M, Esposito R, Leone L, Donizetti A, Crispi S, Rienzo M, Sarubbi B, Calabrò R, Picardi M, Salvatore P, Infante T, De Berardinis P, Napoli C, Ciccodicola A. Massive-scale RNA-seq analysis of non ribosomal transcriptome in human trisomy 21. PLoS ONE April 2011 Volume 6 Issue 4 www.plosone.org