I study the first genetic mouse model of stuttering.
Speech is an innate human trait. The genes and neural circuitry that have evolved to make speech seem effortless remain largely unknown. One way to study the genetic and neural underpinnings of speech is to study when the system goes awry -- to study vocal communication disorders. There are, however, few such disorders that have a known genetic component. One exception is stuttering, which has been linked to mutations in the pathway through which lysosomal enzymes are sorted into lysosomes, the cell’s waste disposal and digestion system.
One such mutation occurs in the gene that codes for the main enzyme in this sorting pathway, GNPTAB. While a complete knock-out of GNPTAB results in mucolipidosis, a devastating disease that causes death in the first decade of life, a less severe missense mutation of GNPTAB results in individuals whose sole clinical manifestation is stuttering (Kang et al. 2010).
An animal model of vocalization is needed to study these genetic phenomena. Often birdsong is used to study speech, however birds are not easily genetically manipulated. Surprisingly, mice have been found to have complex vocalizations throughout their life. These vocalizations are ultrasonic, in the range of 40-100 kHz. As a postdoc, I am studying an animal model of stuttering by examining the vocalizations of mice that have mutations in the lysosomal enzyme sorting pathway.