Search

Objective: Currently, six genes are known to be associated with Usher syndrome type I, and mutations in most of these genes can also cause nonsyndromic hearing loss. The one exception is USH1G, which is currently only known to be involved in Usher syndrome type I and atypical Usher syndrome., Design: A Dutch family with autosomal recessively inherited hearing loss was examined. Audiometric, ophthalmic, and vestibular evaluations were performed besides the genetic analysis., Results: The hearing loss had an early onset with a downsloping audiogram configuration. Slight progression of the hearing loss was seen in both affected individuals. Compound heterozygous mutations in USH1G were found to segregate with the hearing loss in this family, a missense (c.310A>G, p.Met104Val) and a frameshift mutation (c.780insGCAC, p.Tyr261Alafs*96). Extensive ophthalmic and vestibular examinations demonstrated no abnormalities that are usually associated with Usher syndrome type I., Conclusions: This is the first family presented with nonsyndromic hearing loss caused by mutations in USH1G. Our findings expand the phenotypic spectrum of mutations in USH1G.

Objectives: Recently, OTOG and OTOGL were identified as human deafness genes. Currently, only four families are known to have autosomal recessive hearing loss based on mutations in these genes. Because the two genes code for proteins (otogelin and otogelin-like) that are strikingly similar in structure and localization in the inner ear, this study is focused on characterizing and comparing the hearing loss caused by mutations in these genes., Design: To evaluate this type of hearing, an extensive set of audiometric and vestibular examinations was performed in the 13 patients from four families., Results: All families show a flat to downsloping configuration of the audiogram with mild to moderate sensorineural hearing loss. Speech recognition scores remain good (>90%). Hearing loss is not significantly different in the four families and the psychophysical test results also do not differ among the families. Vestibular examinations show evidence for vestibular hyporeflexia., Conclusion: Because otogelin and otogelin-like are localized in the tectorial membrane, one could expect a cochlear conductive hearing loss, as was previously shown in DFNA13 (COL11A2) and DFNA8/12 (TECTA) patients. Results of psychophysical examinations, however, do not support this. Furthermore, the authors conclude that there are no phenotypic differences between hearing loss based on mutations in OTOG or OTOGL. This phenotype description will facilitate counseling of hearing loss caused by defects in either of these two genes.