Detailed clinical features and genotype-phenotype correlation in an OTOF-related hearing loss cohort in Japan.

Mutations in the OTOF gene are a common cause of hereditary hearing loss and the main cause of auditory neuropathy spectrum disorder (ANSD). Although it is reported that most of the patients with OTOF mutations have stable, congenital or prelingual onset severe-to-profound hearing loss, some patients show atypical clinical phenotypes, and the genotype-phenotype correlation in patients with OTOF mutations is not yet fully understood. In this study, we aimed to reveal detailed clinical characteristics of OTOF-related hearing loss patients and the genotype-phenotype correlation. Detailed clinical information was available for 64 patients in our database who were diagnosed with OTOF-related hearing loss. As reported previously, most of the patients (90.6%) showed a "typical" phenotype; prelingual and severe-to-profound hearing loss. Forty-seven patients (73.4%) underwent cochlear implantation surgery and showed successful outcomes; approximately 85-90% of the patients showed a hearing level of 20-39 dB with cochlear implant and a Categories of Auditory Performance (CAP) scale level 6 or better. Although truncating mutations and p.Arg1939Gln were clearly related to severe phenotype, almost half of the patients with one or more non-truncating mutations showed mild-to-moderate hearing loss. Notably, patients with p.His513Arg, p.Ile1573Thr and p.Glu1910Lys showed "true" auditory neuropathy-like clinical characteristics. In this study, we have clarified genotype-phenotype correlation and efficacy of cochlear implantation for OTOF-related hearing loss patients in the biggest cohort studied to date. We believe that the clinical characteristics and genotype-phenotype correlation found in this study will support preoperative counseling and appropriate intervention for OTOF-related hearing loss patients.

Jervell and Lange-Nielsen syndrome with novel KCNQ1 and additional gene mutations.

We encountered a boy with Jervell and Lange-Nielsen syndrome (JLNS) with compound heterozygous KCNQ1 mutations, maternal Trp248Phe and a novel paternal mutation, Leu347Arg. His father showed long QT (LQT) and arrhythmia. His mother was asymptomatic with no ECG abnormalities. The proband and his father had an additional mutation (SNTA1 Thr372Met), which is reportedly related to SIDS. These results suggest that multiple gene mutations influence the phenotype of KCNQ1 mutation-related arrhythmia.

Mutational Spectrum and Clinical Features of Patients with LOXHD1 Variants Identified in an 8074 Hearing Loss Patient Cohort.

Variants of the LOXHD1 gene, which are expressed in hair cells of the cochlea and vestibule, have been reported to cause a progressive form of autosomal recessive non-syndromic hereditary hearing loss, DFNB77. In this study, genetic screening was conducted on 8074 Japanese hearing loss patients utilizing massively parallel DNA sequencing to identify individuals with LOXHD1 variants and to assess their phenotypes. A total of 28 affected individuals and 21 LOXHD1 variants were identified, among which 13 were novel variants. A recurrent variant c.4212 + 1G > A, only reported in Japanese patients, was detected in 18 individuals. Haplotype analysis implied that this variation occurred in a mutational hot spot, and that multiple ancestors of Japanese population had this variation. Patients with LOXHD1 variations mostly showed early onset hearing loss and presented different progression rates. We speculated that the varying severities and progression rates of hearing loss are the result of environmental and/or other genetic factors. No accompanying symptoms, including vestibular dysfunction, with hearing loss were detected in this study. Few studies have reported the clinical features of LOXHD1-gene associated hearing loss, and this study is by far the largest study focused on the evaluation of this gene.