Agnieszka Pollak 1, A,C-G  
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Department of Genetics, Institute of Physiology and Pathology of Hearing, Warsaw/Kajetany, Poland
Oto-Rhino-Laryngology Surgery Clinic, Institute of Physiology and Pathology of Hearing, Warsaw/Kajetany, Poland
A - Research concept and design; B - Collection and/or assembly of data; C - Data analysis and interpretation; D - Writing the article; E - Critical revision of the article; F - Final approval of article;
Agnieszka Pollak   

Agnieszka Pollak, Department of Genetics, Institute of Physiology and Pathology of Hearing, Mokra 17 Str., Kajetany, 05-830, Nadarzyn, Poland, e-mail: a.pollak@ifps.org.pl
Publication date: 2020-04-10
J Hear Sci 2017;7(1):33–40
Intensive studies have been conducted worldwide to elucidate the genetic basis of hearing impairment (HI). The aim of this study was to estimate the prevalence of DFNB1-related HI among patients with cochlear implants (CI).

Material and Methods:
We analyzed 1262 consecutive patients diagnosed with hearing loss who received a CI. At the time of writing this is the largest CI cohort tested for DFNB1 mutations. The search for mutations was done using our 3-step diagnostic approach to DFNB1 testing (3-step DFNB1 approach) comprising a range of molecular methods: multiplex PCR, PCR-RFLP, allele-specific PCR, Sanger sequencing, and real-time PCR with dedicated TaqMan probes.

Our results show that DFNB1 deafness is present in 39.3% of Polish CI recipients. The most commonly detected causative variant in the study group was c.35delG within the GJB2 gene. The majority of the revealed DFNB1 variants were truncating, and related to early HI onset as well as profound hearing loss.

The data conclusively show that mutations in the DFNB1 locus are the main cause of HI among CI patients, and that the proposed 3-step DFNB1 approach is a fast, effective, and economical method for DFNB1 screening

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