Background: Fragile X syndrome (FXS) and Down syndrome (DS) are the two leading genetic causes of intellectual disability, and FXS is the most common known genetic condition associated with autism. Both FXS and DS are associated with significant language impairment, but little is known about expressive language across domains over time or the role…

In recent years, many children from Eastern European orphanages have been adopted by families in the United States. When children begin life with their new families, they experience an abrupt language shift in which the learning of their native language halts as the learning of the new language commences. Without the support of their native…