Novel PTPRQ Mutations Identified in Three Congenital Hearing Loss Patients With Various Types of Hearing Loss

Objectives: We present 3 patients with congenital sensorineural hearing loss (SNHL) caused by novel PTPRQ mutations, including clinical manifestations and phenotypic features. Methods: Two hundred twenty (220) Japanese subjects with SNHL from unrelated and nonconsanguineous families were enrolled in the study. Targeted genomic enrichment with massively parallel DNA sequencing of all known nonsyndromic hearing loss genes was performed to identify the genetic cause of hearing loss. Results: Four novel causative PTPRQ mutations were identified in 3 cases. Case I had progressive profound SNHL with a homozygous nonsense mutation. Case 2 had nonprogressive profound SNHL with a compound heterozygous mutation (nonsense and missense mutation). Case 3 had nonprogressive moderate SNHL with a compound heterozygous mutation (missense and splice site mutation). Caloric test and vestibular evoked myogenic potential (VEMP) test showed vestibular dysfunction in Case I. Conclusion: Hearing loss levels and progression among the present cases were varied, and there seem to be no obvious correlations between genotypes and the phenotypic features of their hearing loss. The PTPRQ mutations appeared to be responsible for vestibular dysfunction.