Autism and language impairment genetically linked

Lorenzo Miodus-Santini an 11-year-old sixth-grader from Princeton, who was classified as autistic at only 13 months old, was never a big talker. As an infant he didn't babble or coo. When he was a toddler beginning to speak, he would learn one word but forget another.

His older brother, Christian, a 15-year-old high school sophomore, shared some similar characteristics – difficulty with reading, processing words and speaking clearly. Doctors said he had language impairments but was not autistic.

New research published online today in the American Journal of Psychiatry, by scientists at Rutgers University and The Research Institute at Nationwide Children's Hospital in Ohio, reveals that there is a genetic link connecting family members with autism like Lorenzo Miodus-Santini to those like his brother, Christian, who have specific language impairment characterized by speech and language difficulties that can't be explained by cognitive or physical problems.

The research project leader Linda Brzustowicz, Rutgers professor and chair of the Department of Genetics, in the School of Arts and Sciences, says that genes in a narrow region of two chromosomes (15q23-26 and 16p12) responsible for oral and written language impairments can result in similar behavioral characteristics with one family member developing autism and the other 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 to be an autism spectrum disorder. Autism effects one in 88 children nationally - with nearly five times as many boys than girls diagnosed - 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," says Brzustowicz, who collaborated on the study with Christopher W. Bartell, principal investigator in the Battelle Center for Mathematical Medicine at Nationwide Children's Hospital. "This research is important because it is hard to understand autism until we find the genes that might be involved."

While scientists don't believe that there is one single gene that causes autism but rather a number of genes that increase the risk, Brzustowicz and her team of researchers are working to identify genetic patterns in these families in order to help gain a better understanding of the mechanisms that lead to autism, a developmental brain disorder that appears in the first three years of life.

In the Rutgers autism study, 79 families - mostly from New Jersey and Pennsylvania - with one child with autism and at least one with specific language impairment underwent 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.