Pj. Govaerts et al., A new autosomal-dominant locus (DFNA12) is responsible for a nonsyndromic,midfrequency, prelingual and nonprogressive sensorineural hearing loss, AM J OTOL, 19(6), 1998, pp. 718-723
Objective: This study aimed to report on the audiologic findings of a nonsy
ndromic autosomal-dominant hearing loss of which the gene (DFNA 12) recentl
y was found to map to chromosome 11q22-24. The study also aimed to propose
and evaluate an algorithm based on the audiometric findings to discriminate
between affected and unaffected family members before genetic linkage anal
ysis.
Study Design: The study design was a retrospective analysis of the audiomet
ric data of genetically affected and unaffected patients.
Setting: The study was conducted at a tertiary referral center.
Patients: A total of 17 genetically affected and 54 unaffected family membe
rs were studied.
Interventions: Purr-tone audiometry with air and bone conduction and constr
uction and evaluation of an algorithm were performed.
Main Outcome Measures: The type and degree of hearing loss as compared to a
ge and gender-dependent values according to the International Organization
for Standardization 7029 standard were measured. For this comparison, the v
ariable "hearing standard deviations" (HSD) is introduced and is defined as
the number of standard deviations that a hearing threshold is lying above
the age and gender-related median at the given frequency. A description of
the algorithm and an evaluation in terms of alpha- and beta-error also were
measured.
Results: The hearing loss is nonsyndromic, sensorineural, moderate-to-moder
ately severe (pure-tone average, 51 dB at age 18 years), with an early onse
t (probably prelingual) and no progression. It affects all frequencies but
mainly the midfrequencies (500, 1,000. and 2,000 Hz). The algorithm consist
s of an analysis of variance to determine the frequency that is most sensit
ive for the genetic trail under study and on the ranking of the family memb
ers according to their hearing loss (HSD) at this frequency. Individual per
sons are labeled as "affected" or "unaffected" according to this ranking.