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Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Missing Genes Tied to Mental Retardation
17 August 2006 (All day)
Three independent research groups have identified a large genetic deletion that causes mental retardation. "They've broken open a bubble of something that's going to lead to a lot of follow up," comments William Dobyns, a developmental neurogeneticist at the University of Chicago, who was not affiliated with any of the studies.
Mental retardation comes in a baffling diversity of conditions and could be caused by hundreds of underlying genetic triggers, only a few of which have been identified. One glimmer of hope is the advent of detailed scans of individuals' genomes, which are powerful tools in the search for mutations. However, they yield a deluge of data. Focusing in, researchers in the Netherlands, the United Kingdom, and at the University of Washington (UW) in Seattle decided to take aim at "hot spots" on the genome. These regions are flanked by duplicated genetic sequences prone to rearrangement, which can lead to the accidental loss of genes.
Each team examined a different population of people, ranging in size from 50 to 1200, with various kinds of mental retardation. They found that a small number were missing the same six genes on chromosome 17. Two of these genes, when deleted, are thought to be involved with mental retardation. The data suggest that the deletion could be involved in about 1% of all cases of mental retardation, the researchers report online 13 August in a trio of papers in Nature Genetics.
All three teams found these deletions in children, so they decided to check their parents' genomes. The region turned out to be inverted in all the parents. This suggests that the children of parents with inversions are predisposed to the deletion, says Evan Eichler, a human geneticist who led the UW effort.
Although other studies suggest that one out of every five Caucasians of European ancestry may have this inversion, just how many will have children with the deletion is unknown. One problem is the small size of the studies, Eichler notes. To learn more about the deleted genes and their function, scientists need to study more people with the genomic deletion, he says, which is something his team is addressing now.