3.1 Clinical manifestations and genetic results
The clinical manifestations, genetic results in the four patients are shown in Table 1. The patients had no mental retardation or growth delay. All patients failed newborn hearing screening and were diagnosed with bilateral profound HI soon after birth. They all presented typical BOR syndrome with at least two major and two minor items according to the criteria by Chang et al (1). Physical examination revealed preauricular pits in all cases but branchial anomalies just existed in Case 2 and 4 , who also had family history of hearing loss. Bone imaging studies using high-resolution computerized tomography revealed abnormal inner ear structures in all three patients. Three cases showed cochlear nerve dysplasia. Additionally, genetic examination was performed in all cases, case 2 using whole-exome sequencing, case 1,3,4 using Hereditary Hearing Loss panel assay (Mygenostics Corporation, Beijing, PRC). Pathogenic variants in the EYA1 gene were identified only in case 4, which had been reported to be causally linked to BOR syndrome.
Early intervention with hearing aids was provided, and all the patient benefitted little from intensive aural rehabilitation.