Conclusion: The DFNY1 phenotypes shared many characteristics with some autosomal dominant hearing loss, in the aspects of age of onset, severity and audiometric configuration. However, the typical, outstanding feature of this trait was its remarkable pattern of inheritance. Similar traits, if ever encountered, can be most easily identified by discerning this exceptional and rare pattern of inheritance.
Objectives: To analyze the audiological features in Chinese Y-linked non-syndromic hearing impairment, the extended DFNY1 family.
Subjects and methods: A nine-generation Chinese family (DFNY1) was ascertained and expanded from the year of 2000 to 2006. The audiometric evaluations included pure-tone audiometry, tympanometry, and auditory brainstem responses. Some subjects received computerized tomography scan of the temporal bone.
Results: 52 out of 276 members in this family received clinical examinations. 24 live subjects had hearing impairment consisting of 23 patrilineal males and one female. In the affected lineage, 92% patrilineal males were well characterized as having hearing loss and 2 children remained to be diagnosed. Based on the audiological examinations on the male members, the degree of hearing loss was from mild (3 patients), moderate (7 patients) to severe (11 patients). The audiometry displayed 48% subjects with sloping in high frequencies, 38% flat in all frequencies, and the rest (14%) the U-shape. The age of onset ranged from 5-27 years with the average of 11.5 years.