Connecticut investigators planning genetic studies of the body of Adam Lanza, who shot himself and 27 other people in the Dec. 14 school massacre, are unlikely to find clues about mental illness or violent behavior.
Very few genes are linked closely enough to psychiatric disorders to give a clear diagnosis, and there are even fewer links to violent behavior, according to geneticists who aren’t involved in analyzing the Newtown, Connecticut, killer’s DNA. Releasing genetic findings about 20-year-old Lanza -- who killed 20 children and seven adults, including his mother -- may even mislead the public about the relationship between genes, mental illness and violence, said Robert Nussbaum, a geneticist at the University of California, San Francisco.
“It’s a shot in the dark that’s unlikely to show anything,” Nussbaum said in a telephone interview yesterday. “If they find something associated with autism, I’m afraid that it might have the effect of stigmatizing autistic people. I can see a whole morass coming out of this.”
Police and crime investigators are working to understand why Lanza shot his mother, then forced his way into Sandy Hook Elementary School and opened fire. Genetic testing of Lanza’s tissue is “in the early planning stages,” according to a statement today from the office of Wayne Carver, Connecticut’s Chief Medical Examiner.
The University of Connecticut Health Center in Farmington confirmed that they have been asked to assist with Carver’s investigation, saying that their role has “not been entirely determined yet.” Health center officials declined to comment further, referring questions to the medical examiner’s office.
Louise Tambascio, a friend of Lanza’s mother for 12 years, said last week that he was believed to have had Asperger’s syndrome, a developmental disability that is a form of autism. The Associated Press, citing a law-enforcement official, reported that Lanza had a personality disorder, a class of mental illnesses that can range from schizoid to obsessive-compulsive disorders.
“There is absolutely no evidence or any reliable research that suggests a linkage between autism and planned violence,” the Autism Society said Dec. 15 in a statement. “Please do not judge any individual with autism based on what is being said about a killer of innocent children and teachers.”
While a number of genetic mutations have recently been linked to autism, Asperger’s syndrome and other related disorders, the vast majority of cases have no known cause, Wendy Chung, a clinical geneticist at Columbia University in New York. Scientists may use tests called microarrays that can quickly search through the genome for the known flaws, she said.
Tests for the mutations are far from conclusive, geneticists said. Many people who have the DNA mutations that are associated with the disease don’t have autism. And if the mutations don’t appear, this wouldn’t rule out autism, because less than 10 percent of the genetic causes of autism have been discovered, said Heidi Rehm, a geneticist at Harvard Medical School and Brigham & Women’s Hospital in Boston. However, the presence of certain mutations might give more information about the type of mental illness Lanza suffered from, if any, she said.
“If they found a specific abnormality that’s been published and associated with patients, you might be able to look at those patients to get some insight into the issues you’re dealing with, rather than the entire gamut of mental illness,” she said in a telephone interview.
Research attempting to link genes to violence has yielded few results, UCSF’s Nussbaum said. In the 1960s, some scientists claimed that people with an extra copy of the Y chromosome, which is unique to males, were prone to violent behavior, because a disproportionate number of them were in prisons.
Those claims were later disproven, when it was determined that people with the extra chromosome weren’t found in higher rates in prison and most were convicted of nonviolent crimes, he said. It was later shown that the vast majority of people with two Y chromosomes appear normal and are never diagnosed, he said.
A DNA scan might look for mutations in a gene, called MAOA, that makes a substance called monoamine oxidase, Nussbaum said. Very rare mutations in this gene have been associated with a condition called Brunner syndrome described in a large Dutch family in 1993. People with the gene displayed mild mental retardation and violent behavior, following childhood maltreatment.
“My guess is if they were going to look at anything it would be this,” Nussbaum said.
Genetic diagnosis can often help resolve families’ questions about relatives suffering from poorly understood conditions, and perhaps better manage their treatment, said Robert Green, a Harvard geneticist who is studying the use of genetics in primary care. That reasoning doesn’t apply in the Newtown case, he said.
Mental illness and gun-related violence each have underpinnings in a wide variety of social factors that can’t be found in the genome, Green said. Blaming Lanza’s genes for his behavior would distract from discussions of issues such as gun control and care for the mentally ill, he said.
“It makes me uneasy,” Green said. “More and more people are looking to understand mental illness through sensationalized situations like this one. Using genetics to understand a person’s illness in a case like this one just distorts the issue.”
Medical examiners and coroners are increasingly asking for genetic studies to be performed in mysterious deaths, violent or otherwise, Chung said.
“Everyone is trying to play this back and figure out if there’s a way to avoid it in the future,” she said in a telephone interview. “Everyone is trying to point a finger of blame at something.”
Chung and Rehm said DNA analysis services have been in demand in unusual or unexplained deaths. DNA testing can tell doctors whether babies reported to have died of Sudden Infant Death Syndrome, or SIDS, have hidden genetic conditions, Chung said. Young people who die of cardiac disease are increasingly tested for genetic flaws linked to heart disorders, Rehm said.
However, trying to diagnose mental illness in a deceased killer is unusual and certainly wouldn’t turn up a cause of violence, geneticists said.
“Post-hoc analysis of anyone’s DNA, after any event, can only prove an association at best, not any sort of causation,” said Gholson Lyon, a geneticist at Cold Spring Harbor Laboratory in New York.