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Hearing Impairment Related to Age in Usher Syndrome Types 1B and 2A
Mariette Wagenaar, MD;
Annelies van Aarem, MD, PhD;
Patrick Huygen, PhD;
Sandra Pieke-Dahl;
William Kimberling, PhD;
Cor Cremers, MD, PhD
Arch Otolaryngol Head Neck Surg. 1999;125:441-445.
Objective To evaluate hearing impairment in 2 common genetic subtypes of Usher syndrome, USH1B and USH2A.
Design Cross-sectional analysis of hearing threshold related to age in patients with genotypes determined by linkage and mutation analysis.
Setting Otolaryngology department, university referral center.
Patients Nineteen patients with USH1B and 27 with USH2A were examined. All participants were living in the Netherlands and Belgium.
Main Outcome Measure Pure tone audiometry of the best ear at last visit.
Results The patients with USH1B had residual hearing without age dependence, with minimum thresholds of 80, 95, and 120 dB at 0.25, 0.5, and 1 to 2 kHz, respectively. Mean thresholds of patients with USH2A were about 45 to 55 dB better than these minimum values. Distinctive audiographic features of patients with USH2A were maximum hearing thresholds of 70, 80, and 100 dB at 0.25, 0.5, and 1 kHz, respectively, only at younger than 40 years. Progression of hearing impairment in USH2A was 0.7 dB/y on average for 0.25 to 4 kHz and could not be explained by presbyacusis alone.
Conclusions The USH1B and USH2A can be easily distinguished by hearing impairment at younger than 40 years at the low frequencies. Hearing impairment in our patients with USH2A could be characterized as progressive.
From the Department of Otorhinolaryngology, University Hospital Nijmegen, Nijmegen, the Netherlands (Drs Wagenaar, van Aarem, Huygen, and Cremers); and Boys Town National Research Hospital, Omaha, Neb (Ms Pieke-Dahl and Dr Kimberling).
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