Molecular basis of hereditary cognitive disorders

Mental retardation is the biggest unsolved problem of Medical Genetics and a major burden for Health Care. Most severe forms of mental retardation are due to chromosome aberrations and gene defects, but so far, only a small proportion of these defects is known. For the mapping and identification of the relevant genetic factors we employ four different complementary strategies: i. investigation of patients with balanced chromosome rearrangements; ii. development and application of methods for high-resolution detection of unbalanced changes in the DNA; iii. systematic search for mutations in families with X-linked mental retardation; and iv. mapping of autosomal recessive gene defects by identifying homozygous genome segments in children of consanguineous parents. During recent years we have already identified numerous molecular causes of cognitive disorders. The characterization of these genes promises major progress for the diagnosis and prevention of mental retardation as well as new insights into normal and disturbed brain development and function.