The Dresden MR Centre

Coordinator:		Prof. Dr. Evelin Schröck
Institution:		Institut für Klinische Genetik, Medizinische Fakultät Carl Gustac Carus, Technische Universität Dresden
Homepage:		tu-dresden.de/die_tu_dresden

Mental retardation is the most common developmental disorder. Although many causes of MR have been clarified, there are still numerous mentally retarded people without a correct diagnosis.
Patients with mental retardation and their families come to our genetic diagnostic and counseling clinic. We interact closely with pediatricians, specialists for neuropediatrics, and our colleagues from the Centre for Social Pediatrics. We perform a detailed clinical phenotype analysis and other investigations using x-rays, MRT and laboratory investigations including the specific analysis of genetic mutations. If a suggested diagnosis could not be confirmed, we use a genome wide search for small deletions and duplications of the DNA as part of our research strategy within MRNET. Molecular Karyotyping by Array CGH analysis with Agilent 244k Arrays allows for the detection of small DNA copy number changes.
Findings are thoroughly evaluated because the DNA regions that are involved in copy number changes may contain genes that could be important for the explanation of the phenotype of the patient once they are lost or duplicated. However, they could also represent copy number variants or polymorphisms, which are found more frequently in our population and may not cause phenotypic abnormalities. Validation of the copy number variants and polymorphisms is corroborated by database analysis and by studying parental DNA or chromosomes using different technologies such as MLPA- or FISH-analysis. Our center has a longstanding experience in investigating structural chromosomal changes with a variety of FISH probes, e.g. more than 8.000 DNA probes such as BACs, PACs or fosmids.
We have started with the analysis of 300 patients and we exchange our results among all participating MRNET groups. Our clinical geneticists and the physicians of all contributing centers work closely together to exchange their knowledge and capitalize on the joint expertise on rare genetic diseases. Once we have identified DNA regions containing candidate genes for MR we will use modern strategies for studying these genes in more patients and for analyzing gene functions within MRNET. We wish to contribute to the identification of gene networks as a basis for diagnosis, prevention and therapy of MR.