The Iowa Language Cohort resulted from two interconnected studies and over a decade of work by the lab of Dr. J. Bruce Tomblin.
A large, population-level cohort of nearly 2,000 Iowan kindergartners were screened for Specific Language Impairment (SLI) by Dr. Tomblin's group in the mid 1990's. This EpiSLI project helped establish the now-accepted rate of SLI occurrence as ~7%. A subset of this cohort was followed for the next ten years as part of a longitudinal study.
Students in the longitudinal study were given a comprehensive battery of language and narrative assessments in 2nd, 4th, 8th and 10th grades, and their teachers and parents completed surveys on academic performance and home life. DNA was also collected from these individuals.
The foresight to collect DNA has given the cohort a second life, when the Iowa Language Cohort data and samples was transferred to Dr. Jacob Michaelson. Dr. Michaelson's lab has undertaken whole genome sequencing of these samples, and also contributed them to GenLang: the largest ever multi-site collaboration on the genetics of language.