Genes behind enlarged brain size, cancer, autism and epilepsy identified

Researchers have discovered new gene mutations associated with markedly enlarged brain size, or megalencephaly. Mutations in three genes, AKT3, PIK3R2 and PIK3CA, were also found to be associated with a constellation of disorders including cancer, hydrocephalus, epilepsy, autism, vascular anomalies and skin growth disorders. The discovery offers several important lessons and hope for the future in medicine. First, the research team led by Seattle Children's Research Institute discovered additional proof that the genetic make-up of a person is not completely determined at the moment of conception. Researchers previously recognized that genetic changes may occur after conception, but this was believed to be quite rare. Second, discovery of the genetic causes of these human diseases, including developmental disorders, may also lead directly to new possibilities for treatment. AKT3, PIK3R2 and PIK3CA are present in all humans, but mutations in the genes are what lead to conditions including megalencephaly, cancer and other disorders. PIK3CA is a known cancer-related gene, and appears able to make cancer more aggressive. Scientists at Boston Children's Hospital recently published similar findings related to PIK3CA and a rare condition known as CLOVES syndrome in the American Journal of Human Genetics. Researchers at Seattle Children's Research Institute will now delve more deeply into the findings, with an aim to uncover even more about the potential medical implications for children. "Based on what we've found, we believe that we can eventually reduce the burden of and need for surgery for kids with hydrocephalus and change the way we treat other conditions, including cancer, autism and epilepsy," said Jean-Baptiste Riviere, PhD, at Seattle Children's Research Institute. "This research truly helps advance the concept of personalized medicine," Riviere added. Drs. Dobyns, Riviere and team made this discovery through exome sequencing, a strategy used to selectively sequence the coding regions of the genome as an inexpensive but effective alternative to whole genome sequencing. An exome is the most functionally relevant part of a genome, and is most likely to contribute to the phenotype, or observed traits and characteristics, of an organism. The study was published online June 24 in Nature Genetics.