Leonard Abbeduto, director of the UC Davis MIND Institute, has received a more than $3.5 million grant from the National Institutes of Health to conduct an examination of the development of language among individuals with fragile X syndrome, the leading inherited cause of intellectual disability and the foremost single-gene cause of autism spectrum disorder.
Abbeduto will lead the five-year-long multi-site study, which will explore language development in a group of adolescent and young adult males with fragile X syndrome, the factors that affect their language development, and the consequences of language impairments for independent functioning in adulthood.
"Parents often ask what the future may hold for their children with fragile X syndrome. This study will help us answer that question by providing information on language skills and independent functioning in adulthood. The study also should give us clues about treatments and therapies that could improve outcomes for people with fragile X syndrome," said Abbeduto, who also is Tsakopoulos-Vismara Endowed Chair in the Department of Psychiatry and Behavioral Sciences.
Abbeduto is an internationally respected expert on the behavioral growth of individuals with intellectual disabilities, particularly their development and use of language. He is the author of numerous studies on the development of language in children and adolescents with fragile X syndrome. The newly funded research will extend that work into adulthood.
The study will focus on a group of 15- to 22-year-old males with fragile X syndrome. It will explore the effects of behavioral, environmental, and biological factors on development of language among these individuals, as well as how linguistic impairments affect adult outcomes, such as independence and participation in the community. The study also will examine how language development in fragile X differs from that in autism spectrum disorder by collecting data from a comparable group of males with autism.
Study sites for the research will be the UC Davis MIND Institute in Sacramento, Calif.; the Department of Psychology at the University of South Carolina in, Columbia, S.C.; and the New York State Institute for Basic Research in Developmental Disabilities in Staten Island, N.Y.
Fragile X syndrome results from a genetic mutation, a trinucleotide (cytosine-guanine-guanine) repeat expansion in a stretch of DNA on the X chromosome. People normally have five to 45 CGG repeats in this region, but the number of CGG repeats can expand beyond normal as the DNA is copied from mother to child. Fragile X syndrome results when the three nucleotides repeat more than 200 times.
The gene involved in fragile X disorders codes for a critical brain protein known as the fragile X mental-retardation protein (FMRP). This protein normally acts as a brake on the production of other proteins associated with learning and memory. When more than 200 CGG repeats are present, the gene for FMRP tends to shut down, resulting in an overproduction of the other proteins. The brain develops too many connections, or synapses, which often are immature and weak.
The resulting cognitive effects range from learning disorders to severe intellectual impairment and often include autism, epilepsy, anxiety disorders and attention-deficit/hyperactivity disorder (ADHD). Affected individuals tend to have associated physical anomalies, including an elongated face, prominent ears and enlarged testicles, as well as connective-tissue abnormalities and mitral-valve prolapse.
Abbeduto became director of the UC Davis MIND Institute in August 2011. He is the recipient of the 2010 Enid and William Rosen Research Award for outstanding contributions to understanding fragile X syndrome from the National Fragile X Foundation. He is a fellow of the American Association on Intellectual and Developmental Disabilities and the author of more than 100 research papers, books and book chapters and has made numerous presentations throughout the nation and the world.