The finding that shared environment is of significant influence in twins has important implications for future research. Because the prenatal environment and early postnatal environment are shared between twins, it is believed that at least some of the environmental factors affecting susceptibility to autism exert their effect during these critical periods of life. Future studies that investigate such twin-shared experiences and their role in enhancing or suppressing genetic susceptibility are likely to advance the understanding of autism.
The study could not pinpoint the specific time period (i.e. early pregnancy, late pregnancy or birth), nor the specific risk factors (i.e. parental age, maternal nutrition, maternal infections during pregnancy, premature and/or underweight birth, etc.) that contribute to the increased risk notes Dr. Lajonchere. "Indeed, multiple-birth pregnancies are themselves associated with increased risk of developmental disorders such as cerebral palsy and autism. This speaks to the importance of further study on what prenatal and perinatal factors increase risk beyond that of inherited genes," she concludes.
AGRE, which Dr. Lajonchere heads, was instrumental in this study. AGRE clinical staff recruited twins to participate and performed the home-based testing of many of the study participants, using scientifically validated research measures for diagnosing autism spectrum disorders. Other institutes involved in the study include: Stanford University, Environmental Health Investigations Branch, California Department of Public Health, Kaiser Permanente Northern California, University of California Davis, MIND Institute, and the Institute for Human Genetics and Department of Epidemiology and Biostatistics, University of California, San Francisco
|Contact: Jane E. Rubinstein|