A novel genetic variant associated with benign paroxysmal positional vertigo within the LOXL1

Hearing Loss in Exfoliation Syndrome: Systematic Review and Meta-Analysis

OBJECTIVE

To determine if exfoliation syndrome (XFS) is associated with hearing loss (HL) or vestibular dysfunction.

DATA SOURCES

PubMed, Scopus, CINAHL, and Cochrane Library through April 1, 2022.

REVIEW METHODS

Two reviewers independently screened abstracts, selected articles for inclusion, and extracted data. Studies included for qualitative analysis conducted audiometric, tympanometric, or vestibular evaluations on all subjects.

RESULTS

Twenty-one publications (1148 patients with XFS and 1212 controls) were included in the systematic review, and 16 publications (968 patients with XFS and 1147 controls) in the meta-analysis. Greater severity of HL was seen for patients with XFS compared to controls across all frequencies (odds ratio [OR] 8.8 [7.3-10.2]). Patients with XFS were more likely to have moderate to profound sensorineural HL (OR 1.8 [1.3-2.5]), and less likely to have none to mild HL (OR 0.34 [0.17-0.67]) or no HL (OR 0.37 [0.28-0.50]). Three studies found patients with XFS had lower tympanometric peaks. Two studies found that abnormal vestibular testing results could be more common for patients with XFS.

CONCLUSIONS

HL is associated with XFS. A sensorineural component to HL is confirmed, and mixed HL is possible. Given the high prevalence and infrequent diagnosis of XFS, the authors hypothesize that the current understandings of presbycusis might be improved by further investigation in XFS. Laryngoscope, 2022.

Identification of a genetic variant underlying familial cases of recurrent benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo in humans, yet the molecular etiology is currently unknown. Evidence suggests that genetic factors may play an important role in some cases of idiopathic BPPV, particularly in familial cases, but the responsible genetic variants have not been identified. In this study, we performed whole exome sequencing [including untranslated regions (UTRs)] of 12 families and Sanger sequencing of additional 30 families with recurrent BPPV in Caucasians from the United States (US) Midwest region, to identify the genetic variants responsible for heightened susceptibility to BPPV. Fifty non-BPPV families were included as controls. In silico and experimental analyses of candidate variants show that an insertion variant rs113784532 (frameshift causing truncation) in the neural cadherin gene PCDHGA10 (protocadherin-gamma A10) is an exceedingly strong candidate (p = 1.80x10-4 vs. sample controls; p = 5.85x10-19 vs. ExAC data; p = 4.9x10-3 vs. NHLBI exome data). The mutant protein forms large aggregates in BPPV samples even at young ages, and affected subjects carrying this variant have an earlier onset of the condition than those without [average 44.0±14.0 (n = 16) versus 54.4±16.1 (n = 36) years old, p = 0.054]. In both human and mouse inner ear tissues, PCDHGA10 is expressed in ganglia, hair cells and vestibular transitional epithelia. Fluorescent RNA in situ hybridization using mouse inner ear tissues shows that expression increases with age. In summary, our data show that a variant in the PCDHGA10 gene may be involved in causing or aggravating some familial cases of recurrent idiopathic BPPV.

A novel genetic variant associated with benign paroxysmal positional vertigo within the LOXL1

Background

Benign paroxysmal positional vertigo (BPPV) is a common, self‐limited, and favorable prognostic peripheral vestibular disorder. BPPV is transmitted in an autosomal dominant fashion, but most cases occur sporadically. Little research has been reported regarding the mutation spectrum of sporadic BPPV in a large cohort. This study attempted to identify the causative candidate variants associated with BPPV in VDR, LOXL1, and LOXL1‐AS1.

Methods

An amplicon‐targeted next‐generation sequencing (NGS) method for VDR, LOXL1, and LOXL1‐AS1, was completed in 726 BPPV patients and 502 normal controls. A total of 30 variants (20 variants from VDR, nine variants from LOXL1, seven variants from LOXL1‐AS1) were identified in these two groups.

Results

Three of 30 variants were nonsynonymous mutations, but no significant difference was found between the BPPV group and the control group via association analysis. A single nucleotide variant (SNV), rs1078967, was identified that is located in intron 1 of LOXL1. The allelic frequency distribution differed significantly between the BPPV group and the control group (p = 0.002). Genotypic frequency was also significantly different (p = 0.006), as determined by gene‐based analyses.

Conclusion

This report is the first to analyze the variant spectrum of BPPV in a large Chinese population.