The use of buccal smears for a non-invasive screening of the 35delG mutation of the Connexin-26 gene in hearing impaired young children Attila Torkos a,b , Magnus Teschner b , Peter Erfurt b , Gerrit Paasche b , Thomas Lenarz b , Timo Sto ¨ver b, * a Clinic of Otorhinolaryngology and Head & Neck Surgery, University of Szeged, Tisza Lajos krt. 111, Szeged 6725, Hungary b Department of Otolaryngology and Head & Neck Surgery, Hannover Medical University, Carl-Neuberg-Straße 1, Hannover 30625, Germany Received 17 June 2005; received in revised form 10 October 2005; accepted 18 October 2005 International Journal of Pediatric Otorhinolaryngology (2006) 70, 965—971 www.elsevier.com/locate/ijporl KEYWORDS Connexin-26; 35delG mutation screening; Buccal smear; Prelingual deafness Summary Objectives: Recent advances in genetic research indicate that about 50% of con- genital deaf patients have a genetic background, with mutations in the Connexin-26 gene being the most frequent one. Screening methods for the genetic cause of deafness have so far mostly been based on the use of peripheral whole blood as DNA source. The use of buccal smears for the genetic screening of deaf patients presents an interesting alternative to drawing blood, especially in young children. In order to validate this method, we compared results from buccal smears from very young deaf children (age  3 years) and deaf patients older than 3 years with the results from blood samples deriving from the same patients. Methods: The detection of the 35delG mutation in the Connexin-26 gene was chosen to demonstrate the method’s feasibility. Blood and buccal smears were collected for genetic analysis from 29 very young deaf children (Group 1: age  3 years) and 31 deaf patients older than 3 years (Group 2) during their clinical pre-evaluation for cochlear implantation. Genomic DNA was isolated from blood as well as from buccal smears. Yield of both sources was determined by photometric evaluation of the isolated DNA concentration. Genomic DNA isolated from blood and buccal smears was then sub- mitted to PCR-mediated site-directed mutagenesis followed by BS1 YI restriction and * Corresponding author. Tel.: +49 0511 532 3808; fax: +49 0511 532 5558. E-mail address: Stoever.Timo@MH-Hannover.de (T. Sto ¨ver). 0165-5876/$ — see front matter # 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijporl.2005.10.007