The majority of rare diseases are hereditary. But despite significant progress in genome research, in most cases their exact cause remains unclear. The discovery of the underlying genetic defect is, however, a prerequisite for their definitive diagnosis and the development of innovative approaches to their treatment. Scientists at the Max Planck Institute for Molecular Genetics and the Institute of Medical Genetics at the Charit Universittsmedizin - Berlin have succeeded in using a new process with which all of the genes in the human genome can be analysed simultaneously. The process was used for the first time on three children in a family who suffer from a rare form of mental retardation (Mabry Syndrome). The analysis revealed a mutation in the PIGV gene that results in the inability of proteins, for example alkaline phosphatase, to anchor to the surface of cell membranes. The results reveal that the new genome sequencing processes are suitable for tracking down individual mutations in the genome and for the identification of these mutations as the cause of rare diseases. (Nature Genetics, August 29th 2010)
The Berlin-based researchers used high throughput sequencing technology for the first time to identify the genetic defect behind a very rare disease. "It was like the proverbial search for a needle in a haystack. We fished out solely the 22,000 genes from the entire genome, decoded their sequence and examined them for mutations. Using new bioinformatic analyses, we were able to limit the number of mutation candidates to two one of which is ultimately responsible for Mabry Syndrome," explains Michal Ruth Schweiger from the Max Planck Institute for Molecular Genetics. The available results will enable, for example, the identification of the genetic risk in affected couples who would like to have children.
Mabry Syndrome is a rare recessive genetic disorder that causes mental retardation, seizures and a characteristic mutation in
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