Category Archives: Transhuman News

By Sheryl Ubelacker, The Canadian Press

TORONTO - As if autism wasn't already enough of a puzzle, researchers have discovered that even siblings affected by the disorder often don't share the same genetic mutations that appear to underlie their symptoms.

In a Canadian-led international study of 85 families with two children affected by autism spectrum disorder (ASD), researchers found that almost 70 per cent of the sibling pairs carried different genetic mutations related to the neurodevelopmental condition.

The scientists made the discovery after analyzing the DNA of both parents and children in a family, using whole genome sequencing.

The technique reads every one of the six billion letters that comprise an individual's genetic code, including those that make up more than 20,000 of a person's genes. Mutations are like typos in the massive encyclopedic tome that is human DNA.

"When we looked at the data, we were really surprised to see that when we could find mutations in genes that are known to be involved in autism, more often than not the siblings were carrying different mutations in different genes," said principal investigator Stephen Scherer, director of the Centre for Applied Genomics at Toronto's Hospital for Sick Children.

"I would have expected that more than one sibling would have carried the same sets of mutations because they both have autism."

Autism is a spectrum of related disorders with symptoms that can vary dramatically from one child to the next, although each will have problems with social skills, empathy, communication and inflexible behaviour. Two children with the same diagnosis say Asperger's syndrome may have very different abilities and behavioural traits.

Even in families with two siblings carrying the same genetic mutation, "in one case they'll be high-functioning and in the other low-functioning," he said.

While the genome results initially came as a surprise, Scherer said that on reflection they made sense: scientists have identified more than 100 genes that are implicated in autism spectrum disorder and they believe there are likely hundreds more.

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Gene profile may differ in siblings with autism

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Newswise PHILADELPHIA Tens of millions of people around the world have abnormal, leak-prone sproutings of blood vessels in the brain called cerebral cavernous malformations (CCMs). These abnormal growths can lead to seizures, strokes, hemorrhages, and other serious conditions, yet their precise molecular cause has never been determined. Now, cardiovascular scientists at the Perelman School of Medicine at the University of Pennsylvania have studied this pathway in heart development to discover an important set of molecular signals, triggered by CCM-linked gene defects, that potentially could be targeted to treat the disorder.

We hope that these findings will lead to a better understanding of the origins of CCM, and thus to treatment possibilities, says Mark L. Kahn, MD, a professor of Cardiovascular Medicine, and senior author of the new study, published in Developmental Cell.

Although CCM has a relatively high prevalence of 1 in 200 people worldwide, it typically goes undiagnosed until symptoms arise and can only be treated by brain surgery.

Research on CCM has been slowed by the difficulty of recreating the disease in lab animals. About 20 percent of CCM patients have a highly aggressive, inherited form of the disorder that is caused by inactivating one of three genes, whose protein products normally work together in a complex. But knockout mice bred without a full set of those genes dont mature to have CCMs in their brainsthey die in the womb, having failed to develop a working vascular system.

Those animals die so early in their development that you just dont get enough information about what the genes normally should be doing, Kahn says.

Studies by Kahns lab and others have shown that CCM gene knockouts remain lethal to fetal mice even when they are limited to the endothelial cells that line blood vessels and the heart.

In the new study, Kahn and colleagues used advanced techniques to restrict CCM gene disruption to the endothelial cells of the developing heart, leaving the mouse vascular system to develop otherwise normally.

The resulting mice still died before birth, this time from a failure of normal heart development, which is not seen in human CCM patients. But they survived in the womb about a week longer than standard CCM knockout mice. That allowed Kahns team to learn more about the effects of the gene disruptions, and ultimately to find a previously unknown CCM-related signaling pathway.

Excerpt from:
Possible Therapeutic Target for Common, But Mysterious Brain Blood Vessel Disorder