Pre-implantation genetic diagnosis (PGD) can give women at risk of passing on a mitochondrial DNA disorder to their offspring a good chance of being able to give birth to an unaffected child, a researcher told the annual conference of the European Society of Human Genetics on May 30, 2011. Dr. Debby Hellebrekers, from Maastricht University Medical Centre, Maastricht, The Netherlands, said that the scientists' findings could have a considerable effect on preventing the transmission of mitochondrial diseases. Mitochondria are cellular organelles involved in the conversion of the energy of food molecules into ATP, the molecule that powers most cellular functions. Disruptions of this energy-producing process, due to a defect in the mitochondrial DNA (mtDNA) or nuclear genes, can cause mitochondrial disorders which represent the most common group of inborn errors of metabolism. The manifestation of mtDNA disorders can be quite varied, but the diseases are almost always serious and, if they do not lead to death, they can result in life-long serious disability for children born with them. Symptoms of mtDNA disorders include loss of muscle co-ordination, visual and hearing problems, poor growth, mental retardation, heart, liver, and kidney disease, neurological problems, respiratory disorders, and dementia. Prenatal diagnosis is in general not possible for mtDNA diseases, because the clinical signs cannot be reliably predicted from the mutation load (the relative amount of mutated mtDNA molecules) in chorionic villus sampling, so the team of scientists from The Netherlands, Australia, and the UK decided to look at whether PGD would be a better alternative. "If we could find a minimal level of mtDNA mutation load below which the chance for an embryo of being affected was acceptably low," said Dr.
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