Whole-exome sequencing suggests multiallelic inheritance for childhood-onset Ménière's disease

The genetic background of Ménière's disease (MD) was studied in one patient with childhood-onset MD and his grandfather affected with middle age-onset MD. Whole-exome sequencing was performed and the data were compared to 76 exomes from unrelated subjects without MD. Thirteen rare inner ear expressed variants with pathogenic estimations were observed in the case of childhood-onset MD. These variants were in genes involved in the formation of cell membranes or the cytoskeleton and in genes participating in cell death or gene-regulation pathways. His grandfather shared two of the variants: p.Y273N in HMX2 and p.L229F in TMEM55B. HMX2 p.Y273N was considered the more likely candidate for MD, as the gene is known to affect both hearing and vestibular function. The variant in the HMX2 gene may affect inner ear development and structural integrity and thus might predispose to the onset of MD. As there was a significant difference in onset between the patients, an accumulation of defects in several pathways is probably responsible for the exceptionally early onset of the disease, and the genetic etiology of childhood-onset MD is most likely multifactorial. This is the first molecular genetic study of childhood-onset MD.