Researchers note that the genes in a narrow region of two chromosomes — responsible for oral and written language impairments — can result in one family member developing autism and another having only language difficulties.
Specific language impairment is one of the most common learning disabilities, affecting an estimated 7 percent of children. It is not considered an autism spectrum disorder.
Autism effects one in 88 children nationally — about half of whom have some degree of language impairment.
“In this group of families we are trying to find genetic factors that might connect them,” said project leader Dr. Linda Brzustowicz, Rutgers professor and chair of the Department of Genetics. “This research is important because it is hard to understand autism until we find the genes that might be involved.”
Although scientists don’t believe that there is one single gene that causes autism but rather several genes that increase the risk, the researchers are working to identify genetic patterns in these families to help gain a better understanding of the mechanisms that lead to autism.
During the study, 79 families who had one child with autism and at least one with specific language impairment went through extensive in-home testing. Besides taking blood samples for genetic testing, family members including parents, children and grandparents and in some cases even uncles, aunts and cousins underwent a battery of tests to assess grammar, vocabulary and language processing.
“Our results indicate that there are shared patterns of DNA and visible behavioral characteristics across our group of study families,” said Judy Flax, Ph.D., an associate research professor working on the study with Brzustowicz.
Researchers also found strong evidence of a genetic link in the areas of obsessive-compulsive, repetitive behaviors and social interaction skills, other symptoms associated with autism.
According to Brzustowicz, the next step will be to sequence the whole genome of those in the study to see if scientists can identify any specific genes or mutations that are common overall.
The research team has been studying the genetic influences of autism on families for the past decade.
“This is just the beginning,” said Brzustowicz. “We are finding evidence of genetic similarities with the hopes of being able to identify targets that might respond to pharmacological treatments.”
Source: American Journal of Psychiatry