New frontiers in understanding speech sound disorder: Unraveling the mysteries of genetic causes

The nature of speech sound disorder (SSD) is not yet well understood. Some view it as a single clinical entity, while others propose distinct subtypes, defined variously by criteria such as error types and suspected cause. A universally accepted disorder classification, based on relevant behavioral observations, does not yet exist. An account of genetic substrates would greatly enhance current understanding of SSD, but such an account is not yet available. This chapter reviews the history of genetic research in SSD from the first studies of familial clustering of SSD to the most recent studies in molecular genetics and points to new frontiers in the quest to characterize the biological causes of SSD.