The incorporation of genetic information into the early hearing detection and intervention (EHDI) process has the potential to dramatically improve the process by providing information regarding appropriate protocols for case management and differential diagnosis, prognosis for rehabilitation and by providing more complete information for families regarding etiology and recurrence risk. However, before genetic testing should be applied universally, it is important to understand when to introduce such testing and counseling into the process and these decisions should be based on scientific study and data. Relative to other events in the EHDl process, the time at which the family is approached regarding testing and the provision of information will influence parental interest in genetic testing, parental understanding of information provided, and the anxiety associated with the information. Further, before Cx26 genetic testing is applied universally, it is important to understand how the limitations of genetic testing at a single locus for a heterogeneous condition influences parental understanding, anxiety, and perceived personal control. Only through prospective, longitudinal research designs will data bearing on these important issues be available. The accuracy and completeness of information regarding prognosis relative to genetic disposition is linked to the amount of carefully controlled phenotype investigations. At present, a lack of large-scale studies of the hearing and related characteristics (phenotype) of infants and children with accurate genotypic information have denied the hearing health community with a complete picture of the infant with biallelic Cx26 mutations. This study employs a prospective, longitudinal design to compare the efficacy of introducing genetic counseling and testing at two stages in the EHDI process, one after failure on inpatient screening but before final diagnosis (pre-diagnosis) and the other following audiologic diagnosis of hearing loss (post-diagnosis). A large cohort of predominantly hearing parents will be followed for up to 6 months to fully evaluate the educational and psychological outcomes of genetic testing and counseling. A large cohort of infants and toddlers will be followed for up to three years to fully evaluate the audiologic phenotype of infants and data will be compared based on Cx26 genotype.
