BACKGROUND. Sensorineural hearing impairment (SNHI) is the most common inherited sensory defect, affecting about 3 per 1000 children. More than 50% of these patients have a genetic cause (i.e. hereditary hearing impairment; HHI). Mutations in certain genes were noted to be extraordinarily popular in the deaf patients across different populations, making molecular screening feasible for these common deafness genes. One of the most important characteristics that we have learned concerning hereditary hearing loss is that common deafness genes and their mutations are usually different according to the ethnic background. As demonstrated in our previous studies performed in Taiwanese patients, the mutation spectrums of common deafness genes, such as the GJB2 gene and the SLC26A4 gene, are different from those in the Caucasian or even other Asian populations. These findings further underscore the indispensability of the collection of local data in terms of genetic counseling. In the collaborative project, we have successfully established a cohort of >100 hearingimpaired families, and clarified the genetic epidemiology of deafness in the Mongolian population. We identified several special deafness mutations such as GJB2 c.23+1G>A, c.559_604dup, and SLC26A4 c.919-2A>G, and our results revealed that Mongolian patients demonstrate a unique genetic profile in deafness as compared to other East Asian populations (paper in preparation). Meanwhile, by organizing a seminar at National Taiwan University Hospital in March 2017, we have transferred crucial concepts and techniques regarding how to perform genetic testing for deafness to the Mongolian colleagues. In the future, we plan to strengthen the mutual collaboration by expanding the clinical cohort and upgrading the genetic examination platform using the NGS techniques.